Method and terminal for carrying out access control in 5th generation mobile communication system

ABSTRACT

Provided is a method for carrying out access control in a radio resource control (RRC) connected mode according to a disclosure of the present specification. The method may comprise the steps of: a non-access stratum (NAS)layer of a terminal determining an access category if outgoing (MO) data to be transmitted or outgoing (MO) signaling occurs; the NAS layer transmitting the NAS signaling message and access category to an access stratum (AS) layer if no disconnection is determined as a result of carrying out a termination test for access control on the basis of the access category; and the AS stratum of the terminal transmitting, to a base station, an RRC message comprising at least one from among the access category, call type, and reason for setup.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Stage filing under 35 U.S.C. 371 ofInternational Application No. PCT/KR2018/000244, filed on Jan. 5, 2018,which claims the benefit of U.S. Provisional Applications No. 62/442,990filed on Jan. 6, 2017, No. 62/490,533 filed on Apr. 26, 2017, No.62/545,430 filed on Aug. 14, 2017, No. 62/545,487 filed on Aug. 15,2017, No. 62/564,317 filed on Sep. 28, 2017, No. 62/572,584 filed onOct. 16, 2017, and No. 62/586,136 filed on Nov. 14, 2017, the contentsof which are all hereby incorporated by reference herein in theirentirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to mobile communication.

Related Art

In 3GPP in which technical standards for mobile communication systemsare established, in order to handle 4th generation communication andseveral related forums and new technologies, research on Long TermEvolution/System Architecture Evolution (LTE/SAE) technology has startedas part of efforts to optimize and improve the performance of 3GPPtechnologies from the end of the year 2004.

SAE that has been performed based on 3GPP SA WG2 is research regardingnetwork technology that aims to determine the structure of a network andto support mobility between heterogeneous networks in line with an LTEtask of a 3GPP TSG RAN and is one of recent important standardizationissues of 3GPP. SAE is a task for developing a 3GPP system into a systemthat supports various radio access technologies based on an IP, and thetask has been carried out for the purpose of an optimized packet-basedsystem which minimizes transmission delay with a more improved datatransmission capability.

An Evolved Packet System (EPS) higher level reference model defined in3GPP SA WG2 includes a non-roaming case and roaming cases having variousscenarios, and for details therefor, reference can be made to 3GPPstandard documents TS 23.401 and TS 23.402. A network configuration ofFIG. 1 has been briefly reconfigured from the EPS higher level referencemodel.

FIG. 1 shows the configuration of an evolved mobile communicationnetwork.

An Evolved Packet Core (EPC) may include various elements. FIG. 1illustrates a Serving Gateway (S-GW) 52, a Packet Data Network Gateway(PDN GW) 53, a Mobility Management Entity (MME) 51, a Serving GeneralPacket Radio Service (GPRS) Supporting Node (SGSN), and an enhancedPacket Data Gateway (ePDG) that correspond to some of the variouselements.

The S-GW 52 is an element that operates at a boundary point between aRadio Access Network (RAN) and a core network and has a function ofmaintaining a data path between an eNodeB 22 and the PDN GW 53.Furthermore, if a terminal (or User Equipment (UE) moves in a region inwhich service is provided by the eNodeB 22, the S-GW 52 plays a role ofa local mobility anchor point. That is, for mobility within an E-UTRAN(i.e., a Universal Mobile Telecommunications System (Evolved-UMTS)Terrestrial Radio Access Network defined after 3GPP release-8), packetscan be routed through the S-GW 52. Furthermore, the S-GW 52 may play arole of an anchor point for mobility with another 3GPP network (i.e., aRAN defined prior to 3GPP release-8, for example, a UTRAN or GlobalSystem for Mobile communication (GSM) (GERAN)/Enhanced Data rates forGlobal Evolution (EDGE) Radio Access Network).

The PDN GW (or P-GW) 53 corresponds to the termination point of a datainterface toward a packet data network. The PDN GW 53 can support policyenforcement features, packet filtering, charging support, etc.Furthermore, the PDN GW (or P-GW) 53 can play a role of an anchor pointfor mobility management with a 3GPP network and a non-3GPP network(e.g., an unreliable network, such as an Interworking Wireless LocalArea Network (I-WLAN), a Code Division Multiple Access (CDMA) network,or a reliable network, such as WiMax).

In the network configuration of FIG. 1, the S-GW 52 and the PDN GW 53have been illustrated as being separate gateways, but the two gatewaysmay be implemented in accordance with a single gateway configurationoption.

The MME 51 is an element for performing the access of a terminal to anetwork connection and signaling and control functions for supportingthe allocation, tracking, paging, roaming, handover, etc. of networkresources. The MME 51 controls control plane functions related tosubscribers and session management. The MME 51 manages numerous eNodeBs22 and performs conventional signaling for selecting a gateway forhandover to another 2G/3G networks. Furthermore, the MME 51 performsfunctions, such as security procedures, terminal-to-network sessionhandling, and idle terminal location management.

The SGSN handles all packet data, such as a user's mobility managementand authentication for different access 3GPP networks (e.g., a GPRSnetwork and an UTRAN/GERAN).

The ePDG plays a role of a security node for an unreliable non-3GPPnetwork (e.g., an I-WLAN and a Wi-Fi hotspot).

As described with reference to FIG. 1, a terminal (or UE) having an IPcapability can access an IP service network (e.g., IMS), provided by aservice provider (i.e., an operator), via various elements within an EPCbased on non-3GPP access as well as based on 3GPP access.

Furthermore, FIG. 1 shows various reference points (e.g., S1-U andS1-MME). In a 3GPP system, a conceptual link that connects two functionsthat are present in the different function entities of an E-UTRAN and anEPC is called a reference point. Table 1 below defines reference pointsshown in FIG. 1. In addition to the reference points shown in theexample of Table 1, various reference points may be present depending ona network configuration.

TABLE 1 REFERENCE POINT DESCRIPTION S1-MME A reference point for acontrol plane protocol between the E-UTRAN and the MME S1-U A referencepoint between the E-UTRAN and the S-GW for path switching betweeneNodeBs during handover and user plane tunneling per bearer S3 Areference point between the MME and the SGSN that provides the exchangeof pieces of user and bearer information for mobility between 3GPPaccess networks in idle and/or activation state. This reference pointcan be used intra-PLMN or inter-PLMN (e.g. in the case of Inter-PLMNHO). S4 A reference point between the SGW and the SGSN that providesrelated control and mobility support between the 3GPP anchor functionsof a GPRS core and the S-GW. Furthermore, if a direct tunnel is notestablished, the reference point provides user plane tunneling. S5 Areference point that provides user plane tunneling and tunnel managementbetween the S-GW and the PDN GW. The reference point is used for S- GWrelocation due to UE mobility and if the S-GW needs to connect to anon-collocated PDN GW for required PDN connectivity S11 A referencepoint between the MME and the S-GW SGi A reference point between the PDNGW and the PDN. The PDN may be a public or private PDN external to anoperator or may be an intra-operator PDN, e.g., for the providing of IMSservices. This reference point corresponds to Gi for 3GPP access.

Among the reference points shown in FIG. 1, S2a and S2b correspond tonon-3GPP interfaces. S2a is a reference point providing the user planewith related control and mobility support between a PDN GW and areliable non-3GPP access. S2b is a reference point providing the userplane with mobility support and related control between a PDN GW and anePDG.

FIG. 2 is an exemplary diagram showing the architecture of a commonE-UTRAN and a common EPC.

As shown in FIG. 2, the eNodeB 20 can perform functions, such as routingto a gateway while RRC connection is activated, the scheduling andtransmission of a paging message, the scheduling and transmission of abroadcast channel (BCH), the dynamic allocation of resources to UE inuplink and downlink, a configuration and providing for the measurementof the eNodeB 20, control of a radio bearer, radio admission control,and connection mobility control. The EPC can perform functions, such asthe generation of paging, the management of an LTE_IDLE state, theciphering of a user plane, control of an EPS bearer, the ciphering ofNAS signaling, and integrity protection.

FIG. 3 is an exemplary diagram showing the structure of a radiointerface protocol in a control plane between UE and an eNodeB, and FIG.4 is another exemplary diagram showing the structure of a radiointerface protocol in a control plane between UE and an eNodeB.

The radio interface protocol is based on a 3GPP radio access networkstandard. The radio interface protocol includes a physical layer, a datalink layer, and a network layer horizontally, and it is divided into auser plane for the transmission of information and a control plane forthe transfer of a control signal (or signaling).

The protocol layers may be classified into a first layer (L1), a secondlayer (L2), and a third layer (L3) based on three lower layers of theOpen System Interconnection (OSI) reference model that is widely knownin communication systems.

The layers of the radio protocol of the control plane shown in FIG. 3and the radio protocol in the user plane of FIG. 4 are described below.

The physical layer PHY, that is, the first layer, provides informationtransfer service using physical channels. The PHY layer is connected toa Medium Access Control (MAC) layer placed in a higher layer through atransport channel, and data is transferred between the MAC layer and thePHY layer through the transport channel. Furthermore, data istransferred between different PHY layers, that is, PHY layers on thesender side and the receiver side, through the PHY layer.

A physical channel is made up of multiple subframes on a time axis andmultiple subcarriers on a frequency axis. Here, one subframe is made upof a plurality of symbols and a plurality of subcarriers on the timeaxis. One subframe is made up of a plurality of resource blocks, and oneresource block is made up of a plurality of symbols and a plurality ofsubcarriers. A Transmission Time Interval (TTI), that is, a unit timeduring which data is transmitted, is 1 ms corresponding to one subframe.

In accordance with 3GPP LTE, physical channels that are present in thephysical layer of the sender side and the receiver side can be dividedinto a Physical Downlink Shared Channel (PDSCH) and a Physical UplinkShared Channel (PUSCH), that is, data channels, and a Physical DownlinkControl Channel (PDCCH), a Physical Control Format Indicator Channel(PCFICH), a Physical Hybrid-ARQ Indicator Channel (PHICH), and aPhysical Uplink Control Channel (PUCCH), that is, control channels.

A PCFICH that is transmitted in the first OFDM symbol of a subframecarries a Control Format Indicator (CFI) regarding the number of OFDMsymbols (i.e., the size of a control region) used to send controlchannels within the subframe. A wireless device first receives a CFI ona PCFICH and then monitors PDCCHs.

Unlike a PDCCH, a PCFICH is transmitted through the fixed PCFICHresources of a subframe without using blind decoding.

A PHICH carries positive-acknowledgement (ACK)/negative-acknowledgement(NACK) signals for an uplink (UL) Hybrid Automatic Repeat reQuest(HARQ). ACK/NACK signals for UL data on a PUSCH that is transmitted by awireless device are transmitted on a PHICH.

A Physical Broadcast Channel (PBCH) is transmitted in four former OFDMsymbols of the second slot of the first subframe of a radio frame. ThePBCH carries system information that is essential for a wireless deviceto communicate with an eNodeB, and system information transmittedthrough a PBCH is called a Master Information Block (MIB). In contrast,system information transmitted on a PDSCH indicated by a PDCCH is calleda System Information Block (SIB).

A PDCCH can carry the resource allocation and transport format of adownlink-shared channel (DL-SCH), information about the resourceallocation of an uplink shared channel (UL-SCH), paging information fora PCH, system information for a DL-SCH, the resource allocation of anupper layer control message transmitted on a PDSCH, such as a randomaccess response, a set of transmit power control commands for pieces ofUE within a specific UE group, and the activation of a Voice overInternet Protocol (VoIP). A plurality of PDCCHs can be transmittedwithin the control region, and UE can monitor a plurality of PDCCHs. APDCCH is transmitted on one Control Channel Element (CCE) or anaggregation of multiple contiguous CCEs. A CCE is a logical allocationunit used to provide a PDCCH with a coding rate according to the stateof a radio channel A CCE corresponds to a plurality of resource elementgroups. The format of a PDCCH and the number of bits of a possible PDCCHare determined by a relationship between the number of CCEs and a codingrate provided by CCEs.

Control information transmitted through a PDCCH is called DownlinkControl Information (DCI). DCI can include the resource allocation of aPDSCH (also called a downlink (DL) grant)), the resource allocation of aPUSCH (also called an uplink (UL) grant), a set of transmit powercontrol commands for pieces of UE within a specific UE group, and/or theactivation of a Voice over Internet Protocol (VoIP).

Several layers are present in the second layer. First, a Medium AccessControl (MAC) layer functions to map various logical channels to varioustransport channels and also plays a role of logical channel multiplexingfor mapping multiple logical channels to one transport channel. The MAClayer is connected to a Radio Link Control (RLC) layer, that is, ahigher layer, through a logical channel. The logical channel isbasically divided into a control channel through which information ofthe control plane is transmitted and a traffic channel through whichinformation of the user plane is transmitted depending on the type oftransmitted information.

The RLC layer of the second layer functions to control a data size thatis suitable for sending, by a lower layer, data received from a higherlayer in a radio section by segmenting and concatenating the data.Furthermore, in order to guarantee various types of QoS required byradio bearers, the RLC layer provides three types of operation modes: aTransparent Mode (TM), an Un-acknowledged Mode (UM), and an AcknowledgedMode (AM). In particular, AM RLC performs a retransmission functionthrough an Automatic Repeat and Request (ARQ) function for reliable datatransmission.

The Packet Data Convergence Protocol (PDCP) layer of the second layerperforms a header compression function for reducing the size of an IPpacket header containing control information that is relatively large insize and unnecessary in order to efficiently send an IP packet, such asIPv4 or IPv6, in a radio section having a small bandwidth when sendingthe IP packet. Accordingly, transmission efficiency of the radio sectioncan be increased because only essential information is transmitted inthe header part of data. Furthermore, in an LTE system, the PDCP layeralso performs a security function. The security function includesciphering for preventing the interception of data by a third party andintegrity protection for preventing the manipulation of data by a thirdparty.

A Radio Resource Control (RRC) layer at the highest place of the thirdlayer is defined only in the control plane and is responsible forcontrol of logical channels, transport channels, and physical channelsin relation to the configuration, re-configuration, and release of RadioBearers (RBs). Here, the RB means service provided by the second layerin order to transfer data between UE and an E-UTRAN.

If an RRC connection is present between the RRC layer of UE and the RRClayer of a wireless network, the UE is in an RRC_CONNECTED state. Ifnot, the UE is in an RRC_IDLE state.

An RRC state and an RRC connection method of UE are described below. TheRRC state means whether or not the RRC layer of UE has been logicallyconnected to the RRC layer of an E-UTRAN. If the RRC layer of UE islogically connected to the RRC layer of an E-UTRAN, it is called theRRC_CONNECTED state. If the RRC layer of UE is not logically connectedto the RRC layer of an E-UTRAN, it is called the RRC_IDLE state. SinceUE in the RRC_CONNECTED state has an RRC connection, an E-UTRAN cancheck the existence of the UE in a cell unit, and thus control the UEeffectively. In contrast, if UE is in the RRC_IDLE state, an E-UTRANcannot check the existence of the UE, and a core network is managed in aTracking Area (TA) unit, that is, an area unit greater than a cell. Thatis, only the existence of UE in the RRC_IDLE state is checked in an areaunit greater than a cell. In such a case, the UE needs to shift to theRRC_CONNECTED state in order to be provided with common mobilecommunication service, such as voice or data. Each TA is classifiedthrough Tracking Area Identity (TAI). UE can configure TAI throughTracking Area Code (TAC), that is, information broadcasted by a cell.

When a user first turns on the power of UE, the UE first searches for aproper cell, establishes an RRC connection in the corresponding cell,and registers information about the UE with a core network. Thereafter,the UE stays in the RRC_IDLE state. The UE in the RRC_IDLE state(re)selects a cell if necessary and checks system information or paginginformation. This process is called camp on. When the UE in the RRC_IDLEstate needs to establish an RRC connection, the UE establishes an RRCconnection with the RRC layer of an E-UTRAN through an RRC connectionprocedure and shifts to the RRC_CONNECTED state. A case where the UE inthe RRC_IDLE state needs to establish with an RRC connection includesmultiple cases. The multiple cases may include, for example, a casewhere UL data needs to be transmitted for a reason, such as a callattempt made by a user and a case where a response message needs to betransmitted in response to a paging message received from an E-UTRAN.

A Non-Access Stratum (NAS) layer placed over the RRC layer performsfunctions, such as session management and mobility management.

The NAS layer shown in FIG. 3 is described in detail below.

Evolved Session Management (ESM) belonging to the NAS layer performsfunctions, such as the management of default bearers and the managementof dedicated bearers, and ESM is responsible for control that isnecessary for UE to use PS service from a network. Default bearerresources are characterized in that they are allocated by a network whenUE first accesses a specific Packet Data Network (PDN) or accesses anetwork. Here, the network allocates an IP address available for UE sothat the UE can use data service and the QoS of a default bearer. LTEsupports two types of bearers: a bearer having Guaranteed Bit Rate (GBR)QoS characteristic that guarantees a specific bandwidth for thetransmission and reception of data and a non-GBR bearer having the besteffort QoS characteristic without guaranteeing a bandwidth. A defaultbearer is assigned a non-GBR bearer, and a dedicated bearer may beassigned a bearer having a GBR or non-GBR QoS characteristic.

In a network, a bearer assigned to UE is called an Evolved PacketService (EPS) bearer. When assigning an EPS bearer, a network assignsone ID. This is called an EPS bearer ID. One EPS bearer has QoScharacteristics of a Maximum Bit Rate (MBR) and a Guaranteed Bit Rate(GBR) or an Aggregated Maximum Bit Rate (AMBR).

Meanwhile, in FIG. 3, the RRC layer, the RLC layer, the MAC layer, andthe PHY layer placed under the NAS layer are also collectively called anAccess Stratum (AS).

FIG. 5a is a flowchart illustrating a random access process in 3GPP LTE.

The random access process is used for UE 10 to obtain UL synchronizationwith a base station, that is, an eNodeB 20, or to be assigned UL radioresources.

The UE 10 receives a root index and a physical random access channel(PRACH) configuration index from the eNodeB 20. 64 candidate randomaccess preambles defined by a Zadoff-Chu (ZC) sequence are present ineach cell. The root index is a logical index that is used for the UE togenerate the 64 candidate random access preambles.

The transmission of a random access preamble is limited to specific timeand frequency resources in each cell. The PRACH configuration indexindicates a specific subframe on which a random access preamble can betransmitted and a preamble format.

The UE 10 sends a randomly selected random access preamble to the eNodeB20. Here, the UE 10 selects one of the 64 candidate random accesspreambles. Furthermore, the UE selects a subframe corresponding to thePRACH configuration index. The UE 10 sends the selected random accesspreamble in the selected subframe.

The eNodeB 20 that has received the random access preamble sends aRandom Access Response (RAR) to the UE 10. The random access response isdetected in two steps. First, the UE 10 detects a PDCCH masked with arandom access-RNTI (RA-RNTI). The UE 10 receives a random accessresponse within a Medium Access Control (MAC) Protocol Data Unit (PDU)on a PDSCH that is indicated by the detected PDCCH.

FIG. 5b illustrates a connection process in a radio resource control(RRC) layer.

FIG. 5b shows an RRC state depending on whether there is an RRCconnection. The RRC state denotes whether the entity of the RRC layer ofUE 10 is in logical connection with the entity of the RRC layer ofeNodeB 20, and if yes, it is referred to as RRC connected state, and ifno as RRC idle state.

In the connected state, UE 10 has an RRC connection, and thus, theE-UTRAN may grasp the presence of the UE on a cell basis and may thuseffectively control UE 10. In contrast, UE 10 in the idle state cannotgrasp eNodeB 20 and is managed by a core network on the basis of atracking area that is larger than a cell. The tracking area is a set ofcells. That is, UE 10 in the idle state is grasped for its presence onlyon a larger area basis, and the UE should switch to the connected stateto receive a typical mobile communication service such as voice or dataservice.

When the user turns on UE 10, UE 10 searches for a proper cell and staysin idle state in the cell. UE 10, when required, establishes an RRCconnection with the RRC layer of eNodeB 20 through an RRC connectionprocedure and transits to the RRC connected state.

There are a number of situations where the UE staying in the idle stateneeds to establish an RRC connection, for example, when the userattempts to call or when uplink data transmission is needed, or whentransmitting a message responsive to reception of a paging message fromthe EUTRAN.

In order for the idle UE 10 to be RRC connected with eNodeB 20, UE 10needs to perform the RRC connection procedure as described above. TheRRC connection procedure generally comes with the process in which UE 10transmits an RRC connection request message to eNodeB 20, the process inwhich eNodeB 20 transmits an RRC connection setup message to UE 10, andthe process in which UE 10 transmits an RRC connection setup completemessage to eNodeB 20. The processes are described in further detail withreference to FIG. 6.

1) The idle UE 10, when attempting to establish an RRC connection, e.g.,for attempting to call or transmit data or responding to paging fromeNodeB 20, sends an RRC connection request message to eNodeB 20.

2) When receiving the RRC connection message from UE 10, eNodeB 20accepts the RRC connection request from UE 10 if there are enough radioresources, and eNodeB 20 sends a response message, RRC connection setupmessage, to UE 10.

3) When receiving the RRC connection setup message, UE 10 transmits anRRC connection setup complete message to eNodeB 20. If UE 10successfully transmits the RRC connection setup message, UE 10 happensto establish an RRC connection with eNodeB 20 and switches to the RRCconnected state.

In a conventional 4th generation communication system, i.e., a long termevolution (LTE)/LTE-Advanced (LTE-A) system, various access controlmechanisms (e.g., ACB, EAB, ACDC, SSAC) were developed.

Due to success of 4th generation mobile communication, interest in nextgeneration, i.e., 5th generation (so-called 5G) mobile communication hasincreased and a study thereof is also being conducted.

However, to apply the existing access control mechanism to a 5thgeneration (so-called 5G) mobile communication has an inefficientproblem.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to present a methodthat can solve the aforementioned problem.

In order to achieve the above-described object, disclosures of thepresent invention provide an access control mechanism for 5th generation(so-called 5G) mobile communication.

Specifically, in order to achieve the above-described object, in anaspect, a method of performing access control in a Radio ResourceControl (RRC) connected mode is provided. The method includesdetermining, by a Non-Access Stratum (NAS) layer of a terminal, anaccess category when mobile originating (MO) data or mobile originating(MO) signaling to transmit occurs; transferring, by the NAS layer, a NASsignaling message and the access category to an AS layer, when it isdetermined not to bar as a result of a barring check for access controlbased on the access category; and transmitting, by the Access Stratum(AS) layer of the terminal, an RRC message including at least one of theaccess category, a call type, and an establishment cause to a basestation.

The method may further include receiving, by the AS layer, accesscontrol related information from a network; transferring, by theapplication layer or an IMS layer, an access control start indication tothe NAS layer when the MO data or MO signaling has occurred;transferring, by the NAS layer, the access category to the AS layer; andperforming, by the AS layer, a barring check for the access controlbased on the access category.

The method may further include transferring the received access controlrelated information to the application layer or the IMS layer; anddetermining whether the application layer or the IMS layer shouldperform a barring check for the access control, when MO data or MOsignaling to transmit has occurred in the application layer or the IMSlayer. Here, when it is determined that the barring check should beperformed, the application layer or the IMS layer may transfer theaccess control start indication to the NAS layer.

The method may further include transferring, by the application layer oran IMS layer, an access control start indication to the NAS layer, whenthe MO data or MO signaling has occurred in the application layer or theIMS layer; transferring, by the NAS layer, the access category to the ASlayer; and performing, by the AS layer, a barring check for the accesscontrol based on the access category.

The method may further include obtaining, by the application layer or anIMS layer, the access category from the NAS layer, when MO data or MOsignaling has occurred in the application layer or the IMS layer; andperforming, by the application layer or the IMS layer, a barring checkfor the access control based on the access category.

The NAS signaling message may include a NAS signaling message forSession Management (SM).

The NAS signaling messages for SM may include at least one of a PacketData Unit (PDU) session request message, a PDU session modificationrequest message, a PDU session inactive request message, a PDU sessiondisconnection request message, a PDN connection request message, a PDNdisconnection request message, a bearer resource allocation requestmessage, and a bearer resource modification request message.

The RRC message may include at least one of an RRC Connection setupcomplete message, an RRC connection resume complete message, an RRCconnection reestablishment complete message, an RRC connectionreconfiguration complete message, an RRC active request or completemessage, an RRC inactive request or complete message, a terminalcapability information message, a UL information transfer message, or anew RRC message for an RRC connected mode.

When the determined access category is the multiple number, the barringcheck may be performed for each of all of the plurality of accesscategories.

The method may further include performing a first barring check based ona first category when the determined access category is the multiplenumber; and performing a second barring check based on a second categorywhen it is determined not to bar as a result of the first barring check.

When it is determined to bar as a result of a second barring check, athird barring check may not be performed based on a third accesscategory.

In order to achieve the above-described object, in another aspect, aterminal for performing access control in a Radio Resource Control (RRC)connected mode is provided. The terminal includes a transceiver; and aprocessor configured to control the transceiver.

The processor is configured to determine, by a Non-Access Stratum (NAS)layer of the terminal, an access category, when data or signaling totransmit has occurred; and to transfer, by the NAS layer, a NASsignaling message and the access category to an AS layer, when it isdetermined not to bar as a result of a barring check for access controlbased on an access category; to transmit, by the Access Stratum (AS)layer of the terminal, an RRC message including at least one of theaccess category, a call type, and an establishment cause to a basestation.

According to the present disclosure, the aforementioned problems of therelated art may be solved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structural diagram of an evolved mobile communicationnetwork.

FIG. 2 is an exemplary diagram illustrating architectures of a generalE-UTRAN and a general EPC.

FIG. 3 is an exemplary diagram illustrating a structure of a radiointerface protocol on a control plane between UE and eNodeB.

FIG. 4 is another exemplary diagram illustrating a structure of a radiointerface protocol on a user plane between the UE and a base station.

FIG. 5a is a flowchart illustrating a random access process in 3GPP LTE.

FIG. 5b illustrates a connection process in a radio resource control(RRC) layer.

FIG. 6 shows a network overload state.

FIG. 7 is an exemplary flowchart illustrating an access barringoperation in a network congested state.

FIG. 8 illustrates an example that all accesses by all applications arebarred when ACB is applied.

FIG. 9 is a signal flowchart illustrating a procedure according to theACDC.

FIG. 10 illustrates an example of the Machine Type communication (MTC)communication.

FIG. 11 illustrates an example to which Extended Access Barring (EAB)for solving a congestion caused by an MTC device.

FIG. 12 is a diagram illustrating an expected structure of nextgeneration mobile communication from a node viewpoint.

FIG. 13a is a diagram illustrating an architecture to which a localbreakout (LBO) method is applied upon roaming, and FIG. 13b is a diagramillustrating an architecture to which a home routed (HR) method isapplied upon roaming.

FIG. 14a is a diagram illustrating an example of an architecture forimplementing the concept of network slicing.

FIG. 14b is a diagram illustrating another example of an architecturefor implementing the concept of network slicing.

FIG. 15a illustrates an architecture for interworking when a UE does notperform roaming, and FIG. 15b illustrates an architecture forinterworking when a UE performs roaming.

FIG. 16 is a signal flow diagram illustrating an exemplary procedureaccording to a first disclosure of the present invention.

FIG. 17 is a signal flow diagram illustrating an exemplary procedureaccording to a second disclosure of the present invention.

FIG. 18 is a signal flow diagram illustrating an exemplary procedureaccording to a third disclosure of the present invention.

FIG. 19 is a signal flow diagram illustrating an exemplary procedureaccording to a first scheme of a fourth disclosure.

FIG. 20 is a signal flow diagram illustrating an exemplary procedureaccording to a second scheme of a fourth disclosure.

FIGS. 21a to 21d are diagrams illustrating operations of each layer.

FIG. 22 is a block diagram illustrating a configuration of a UE and anetwork device according to an embodiment of the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The present invention is described in light of UMTS (Universal MobileTelecommunication System) and EPC (Evolved Packet Core), but not limitedto such communication systems, and may be rather applicable to allcommunication systems and methods to which the technical spirit of thepresent invention may apply.

The technical terms used herein are used to merely describe specificembodiments and should not be construed as limiting the presentinvention. Further, the technical terms used herein should be, unlessdefined otherwise, interpreted as having meanings generally understoodby those skilled in the art but not too broadly or too narrowly.Further, the technical terms used herein, which are determined not toexactly represent the spirit of the invention, should be replaced by orunderstood by such technical terms as being able to be exactlyunderstood by those skilled in the art. Further, the general terms usedherein should be interpreted in the context as defined in thedictionary, but not in an excessively narrowed manner.

The expression of the singular number in the specification includes themeaning of the plural number unless the meaning of the singular numberis definitely different from that of the plural number in the context.In the following description, the term ‘include’ or ‘have’ may representthe existence of a feature, a number, a step, an operation, a component,a part or the combination thereof described in the specification, andmay not exclude the existence or addition of another feature, anothernumber, another step, another operation, another component, another partor the combination thereof.

The terms ‘first’ and ‘second’ are used for the purpose of explanationabout various components, and the components are not limited to theterms ‘first’ and ‘second’. The terms ‘first’ and ‘second’ are only usedto distinguish one component from another component. For example, afirst component may be named as a second component without deviatingfrom the scope of the present invention.

It will be understood that when an element or layer is referred to asbeing “connected to” or “coupled to” another element or layer, it can bedirectly connected or coupled to the other element or layer orintervening elements or layers may be present. In contrast, when anelement is referred to as being “directly connected to” or “directlycoupled to” another element or layer, there are no intervening elementsor layers present.

Hereinafter, exemplary embodiments of the present invention will bedescribed in greater detail with reference to the accompanying drawings.In describing the present invention, for ease of understanding, the samereference numerals are used to denote the same components throughout thedrawings, and repetitive description on the same components will beomitted. Detailed description on well-known arts which are determined tomake the gist of the invention unclear will be omitted. The accompanyingdrawings are provided to merely make the spirit of the invention readilyunderstood, but not should be intended to be limiting of the invention.It should be understood that the spirit of the invention may be expandedto its modifications, replacements or equivalents in addition to what isshown in the drawings.

In the drawings, user equipments (UEs) are shown for example. The UE mayalso be denoted a terminal or mobile equipment (ME). The UE may be alaptop computer, a mobile phone, a PDA, a smartphone, a multimediadevice, or other portable device, or may be a stationary device such asa PC or a car mounted device.

DEFINITION OF TERMS

For a better understanding, the terms used herein are briefly definedbefore going to the detailed description of the invention with referenceto the accompanying drawings.

An UMTS is an abbreviation of a Universal Mobile TelecommunicationSystem, and it refers to the core network of the 3rd generation mobilecommunication.

UE/MS is an abbreviation of User Equipment/Mobile Station, and it refersto a terminal device.

An EPS is an abbreviation of an Evolved Packet System, and it refers toa core network supporting a Long Term Evolution (LTE) network and to anetwork evolved from an UMTS.

A PDN is an abbreviation of a Public Data Network, and it refers to anindependent network where a service for providing service is placed.

A PDN connection refers to a connection from UE to a PDN, that is, anassociation (or connection) between UE represented by an IP address anda PDN represented by an APN.

A PDN-GW is an abbreviation of a Packet Data Network Gateway, and itrefers to a network node of an EPS network which performs functions,such as the allocation of a UE IP address, packet screening & filtering,and the collection of charging data.

A Serving gateway (Serving GW) is a network node of an EPS network whichperforms functions, such as mobility anchor, packet routing, idle modepacket buffering, and triggering an MME to page UE.

A Policy and Charging Rule Function (PCRF): The node of an EPS networkwhich performs a policy decision for dynamically applying QoS and abilling policy that are different for each service flow.

An Access Point Name (APN) is the name of an access point that ismanaged in a network and provides to UE. That is, an APN is a characterstring that denotes or identifies a PDN. Requested service or a network(PDN) is accessed via P-GW. An APN is a name (a character string, e.g.,‘internet.mnc012.mcc345.gprs’) previously defined within a network sothat the P-GW can be searched for.

A Tunnel Endpoint Identifier (TEID): The end point ID of a tunnel setbetween nodes within a network, and it is set for each bearer unit ofeach UE.

A NodeB is an eNodeB of a UMTS network and installed outdoors. The cellcoverage of the NodeB corresponds to a macro cell.

An eNodeB is an eNodeB of an Evolved Packet System (EPS) and isinstalled outdoors. The cell coverage of the eNodeB corresponds to amacro cell.

An (e)NodeB is a term that denotes a NodeB and an eNodeB.

An MME is an abbreviation of a Mobility Management Entity, and itfunctions to control each entity within an EPS in order to provide asession and mobility for UE.

A session is a passage for data transmission, and a unit thereof may bea PDN, a bearer, or an IP flow unit. The units may be classified into aunit of the entire target network (i.e., an APN or PDN unit) as definedin 3GPP, a unit (i.e., a bearer unit) classified based on QoS within theentire target network, and a destination IP address unit.

A PDN connection is a connection from UE to a PDN, that is, anassociation (or connection) between UE represented by an IP address anda PDN represented by an APN. It means a connection between entities(i.e., UE-PDN GW) within a core network so that a session can be formed.

UE context is information about the situation of UE which is used tomanage the UE in a network, that is, situation information including aUE ID, mobility (e.g., a current location), and the attributes of asession (e.g., QoS and priority)

OMA DM (Open Mobile Alliance Device Management): a protocol designed formanaging mobile devices such as mobile phones, PDAs, or portablecomputers and performs functions such as device configuration, firmwareupgrade, and error reporting.

OAM (Operation Administration and Maintenance): denotes a group ofnetwork management functions displaying network faults and providingcapability information, diagnosis and data.

NAS configuration MO (Management Object): MO (Management Object) used toconfigure in UE parameter associated with NAS functionality

NAS (Non-Access-Stratum): A higher stratum of a control plane between aUE and an MME. The NAS supports mobility management, session management,IP address management, etc., between the UE and the network.

MM (Mobility Management) operation/procedure: An operation or procedurefor mobility regulation/management/control of the UE. The MMoperation/procedure may be interpreted as including one or more of an MMoperation/procedure in a CS network, a GMM operation/procedure in a GPRSnetwork, and an EMM operation/procedure in an EPS network. The UE andthe network node (e.g., MME, SGSN, and MSC) exchange an MM message toperform the MM operation/procedure.

SM (Session Management) operation/procedure: An operation or procedurefor regulating/managing/processing/handling a user plane and/or a bearercontext/PDP context of the UE. The SM operation/procedure may beinterpreted as including one or more of an SM operation/procedure in aGPRS network and an ESM operation/procedure in an EPS network. The UEand the network node (e.g., MME and SGSN) exchange an SM message toperform the SM operation/procedure.

Low priority UE: A UE configured for NAS signalling low priority. Thestandard document 3GPP TS 24.301 and TS 24.008 may be incorporated byreference for details thereof.

Normal priority UE: A normal UE not configured with low priority.

Dual priority UE: A UE configured for dual priority. That is, a UE whichprovides dual priority support is configured for a NAS signalling lowpriority and also configured to override the NAS signalling low priorityindicator. The standard document 3GPP TS 24.301 and TS 24.008 may beincorporated by reference for details thereof.

PLMN: as an abbreviation of Public Land Mobile Network, means a networkidentification number of a mobile communication provider. In roamingcase of the UE, the PLMN is classifed into a home PLMN (HPLMN) and avistied PLMN (VPLMN).

CIoT: An abbreviation of Cellular Internet of Things, and meansperforming based on IoT communication.

Narrowband-IoT: It refers to radio access technology (RAT) improved in3GPP for CIoT. That is, it is a network operating at a bandwidth of upto 180 kHz (corresponding to one PRB).

Hereinafter, an aspect of the present specification is described withreference to the accompanying drawings.

FIG. 6 shows a network overload state.

As shown in FIG. 6, many UEs 100 a, 100 b, 100 c, and 100 d are presentin the coverage of an eNodeB 200, and data transmission/reception isattempted. Accordingly, if traffic is overloaded or congested in aninterface between the eNodeB 200 and an S-GW 520, downlink data to theMTC device 100 or uplink data from the UE 100 is not correctlytransmitted and thus data transmission fails.

Alternatively, even if an interface between the S-GW 520 and a PDN-GW530 or an interface between the PDN-GW 530 and an Internet Protocol (IP)service network of a mobile communication operator is overloaded orcongested, downlink data to the UEs 100 a, 100 b, 300 c, and 300 d oruplink data from the UEs 100 a, 100 b, 300 c, and 300 d is not correctlytransmitted and thus data transmission fails.

If an interface between the eNodeB 200 and the S-GW 520 is overloaded orcongested or if an interface between the S-GW 520 and the PDN-GW 530 isoverloaded or congested, a node (e.g., MME) of the core network performsa NAS level congest control to avoid or control signaling congestion andAPN congestion.

The NAS level congestion control consists of an APN based congestioncontrol and a general NAS level mobility management control.

The APN based congestion control implies an EMM, GMM, and (E)SM signalcongestion control related to a UE and a specific APN (i.e., an APNrelated to a congestion state), and includes an APN based sessionmanagement congestion control and an APN based mobility managementcongestion control.

On the other hand, the general NAS level mobility management controlimplies that a node (MME, SGSN) in the core network rejects a mobilitymanagement signaling request which is requested by the UE/MS in ageneral network congestion or overload situation to avoid the congestionand the overload.

In general, if the core network performs the NAS level congestioncontrol, a back-off timer value is transmitted to a UE in an idle modeor a connected mode by being carried on a NAS reject message. In thiscase, the UE does not request an EMM/GMM/(E)SM signal to the networkuntil the back-off timer expires. The NAS reject message is one of anAttach reject, a Tracking Area Updating (TAU) reject, a Routing AreaUpdating (RAU) reject, a service reject, an extended service reject, aPDN connectivity reject, a bearer resource allocation reject, a bearerresource modification reject, and a deactivate EPS bearer contextrequest reject.

The back-off timer may be classified into a Mobility Management (MM)back-off timer and a Session Management (SM) back-off timer.

The MM back-off timer operates independently for each UE, and the SMback-off timer operates independently for each APN and each UE.

Simply, the MM back-off timer is for controlling an EMM/GMM signal(e.g., Attach, TAU/RAU request, etc.). The SM back-off timer is forcontrolling an (E)SM signal (e.g., PDN connectivity, Bearer ResourceAllocation, Bearer Modification, PDP Context Activation, PDP ContextModification request, etc.).

More specifically, the MM back-off timer is a mobility managementrelated back-off timer used to control a case where a network congestionoccurs, and is a timer which prevents the UE from performing an attach,location information update (TAU, RAU), and service request procedureduring the timer is running. However, exceptionally in case of anemergency bearer service and a Multimedia Priority Service (MPS), the UEmay be allowed to perform the request even if the timer is running.

As described above, the UE may receive the MM back-off timer value froma core network node (e.g., MME, SGSN, etc.) or from a lower layer(access stratum). In addition, the timer value may be randomly set bythe UE within the range of 15 minutes to 30 minutes.

The SM back-off timer is a session management related back-off timerused to control a case where a network congestion occurs, and is a timerwhich prevents the UE from configuring or changing an associatedAPN-based session. However, likewise, exceptionally in case of anemergency bearer service and a Multimedia Priority Service (MPS), the UE100 may be allowed to perform the request even if the timer is running.

The UE receives the SM back-off timer value from the core network node(e.g., MME, SGSN, etc.), and is randomly set within up to 72 hours. Inaddition, the timer value may be randomly set by the UE/MS within therange of 15 minutes to 30 minutes.

On the other hand, when the congestion occurs in the eNodeB 200, theeNodeB 200 may perform congestion control. That is, when the UE requestsRRC connection establishment for data transmission of the user plane, ifthe eNodeB 200 is in the congest state, the eNodeB 200 may transmit areject response to the UE together with an extended wait timer. In thiscase, the RRC connection establishment request may not be re-attempteduntil the extended wait timer expires. On the contrary, when the UErequests the RRC connection for transmitting the signal of the controlplane for circuit switch (CS)-based call reception, even though theeNodeB 200 is in the congest state, the RRC connection request may notbe rejected.

FIG. 7 is an exemplary flowchart illustrating an access barringoperation in a network congested state.

As illustrated in FIG. 7a , in the overload or congest state of thenetwork or the eNodeB 200, the eNodeB 200 may broadcast access classbarring (ACB)-related information through system information. The systeminformation may be system information block (SIB) type 2.

The SIB type 2 may include ACB-related information like the followingtable.

TABLE 2 Field Description ac-BarringFactor When a random value generatedby the UE is smaller than a value of ac-BarringFactor, access isallowed. If not, the access is barred. ac-BarringForCSFB ACB for circuitswitch (CS) fallback. The CS fallback converts a VoLTE call to aprevious 3G call. ac-BarringForEmergency ACB for emergency serviceac-BarringForMO-Data ACB for mobile orienting data ac-BarringForMO- ACBfor mobile orienting control signal Signalling ac-BarringForSpecialACACB for specific access classes, that is, 11 to 15. ac-BarringTimeRepresents time when the access is barred. ssac-BarringForMMTEL- ACB foreach service for mobile orienting of MMTEL video. Videossac-BarringForMMTEL- ACB for each service for mobile orienting of MMTELvoice. Voice

Meanwhile, UE1 100 a determines an IMS service, for example, mobileorienting of a call by VoLTE and generates a service request message.Similarly, UE2 100 b determines mobile orienting of general data andgenerate the service request message.

Sequentially, the UE1 100 a generates an RRC connection request message.Similarly, the UE2 100 b generate the RRC connection request message.

Meanwhile, the UE1 100 a performs access barring check (that is, whetherthe ACB is applied). Similarly, the UE2 100 b performs access barringcheck (that is, whether the ACB is applied).

If the ACB is not applied, the UE1 100 a and the UE2 100 b may transmita service request (alternatively, an extended service request) messageand the RRC connection request message, respectively. However, when theACB is applied, both the UE1 100 a and the UE2 100 b may not transmitthe RRC connection request message, respectively.

The access barring check will be described in detail as follows.Generally, at least one of 10 access classes (for example, AC0, AC1, . .. , and AC9) is randomly allocated to the UE. Exceptionally, for urgentemergency access, AC10 is allocated. As such, the value of the randomlyallocated access class may be stored in each USIM of the UE1 100 a andthe UE2 100 b. Then, the UE1 100 a and the UE2 100 b verify whether theaccess barring is applied, by using a barring factor included in thereceived ACB-related information, based on the stored access class. Theaccess barring check is performed in each access stratum (AS) layer,that is, an RRC layer of the UE1 100 a and the UE2 100 b.

The access barring check will be described in more detail as follows.

The ac-BarringPerPLMN-List is included in the SIB type 2 received byeach of the UE1 100 a and the UE2 100 b, and in the case whereAC-BarringPerPLMN entry matched with plmn-identityIndex corresponding tothe PLMN selected in an higher layer is included in theac-BarringPerPLMN-List, AC-BarringPerPLMN entry matched with theplmn-identityIndex corresponding to the PLMN selected by the higherlayer is selected.

Next, when the UE1 100 a and the UE2 100 b perform the RRC connectionrequest, the access barring check is performed by using T303 as Tbarringand using ac-BarringForMO-Data as a barring parameter.

When the barring is determined, each AS(RRC) layer of the UE1 100 a andthe UE2 100 b notifies a failure of the RRC connection establishment tothe higher layer.

Subsequently, as such, when the access is barred, each AS(RRC) layerdetermines whether a T302 timer or a Tbarring timer is driving. If thetimer is not driving, the T302 timer or the Marring timer is driven.

Meanwhile, while the T302 timer or a Marring timer is driving, theAS(RRC) layer considers that all the access to the corresponding cell isbarred.

As described above, in the network overload and congest situation, theeNB/RNC provides the ACB-related information to the UE. Then, the UEchecks the access barring by using the barring factor included in thereceived ACB information based on its access class stored in the USIM.Through the access barring check, finally, an access attempt is notperformed. That is, when the access to the corresponding cell is barredthrough the access barring check, the UE does not attempt the access,and when the access to the corresponding cell is not barred, the UEattempts the access. The access barring check is performed in the ASlayer. Herein, the access attempt means that the AS(RRC) layer of the UEtransmits the RRC connection request message to the eNB/RNC.

Meanwhile, an access barring check is performed with respect to a normalMobile Originating (MO) service, for example, an originating call, anoriginating data, an originating IMS voice and an originating IMS video.That is, ACB is applied accesses of all application programs (however,except a response to an urgent service or paging).

FIG. 8 illustrates an example that all accesses by all applications arebarred when ACB is applied.

As can be seen with reference to FIG. 8, when it is determined to applyACB once, accesses by all applications of UE (however, except a responseto an urgent service or paging) are barred.

As such, accesses by all applications are barred, a differentiatedservice is unavailable. Such a problem causes network resource waste anddegrades user experience, consequently.

Accordingly, in a situation of network overload and a congestedsituation, a method is required for differentiating Mobile Originatingservice (e.g., mobile originating voice call or mobile originating data)for each of specific application groups/categories. However, there hasbeen no method for implementing it in the conventional art.

<Introduction of Application Specific Congestion Control DataCommunication (ACDC)>

As a method for differentiating a normal Mobile Originating (MO)service, for example, an originating call, an originating data, anoriginating IMS voice and an originating IMS video, the Applicationspecific Congestion control for Data Communication (ACDC) is proposed.

FIG. 9 is a signal flowchart illustrating a procedure according to theACDC.

The procedure is described with reference to FIG. 9 as below.

First, a network (e.g., eNB) may provide ACDC barring information to aUE through SIB.

Meanwhile, in the case that a specific application is executed in the UE100 and a data communication service is requested by the specificapplication, the application layer that manages the execution of thespecific application provides application attribute related informationto a NAS layer.

Then, the NAS layer of the UE 100 determines an application category forthe ACDC based on the application attribute related information receivedfrom the application layer.

Subsequently, when the NAS layer of the UE 100 starts a service requestprocedure for service connection (a transmission of SERVICE REQUESTmessage or a transmission of EXTENDED SERVICE REQUEST message), the NASlayer of the UE 100 forwards the information for the applicationcategory to an AS layer (i.e., RRC layer).

Before the AS layer (i.e., RRC layer) of the UE 100 performs the servicerequest procedure of the NAS layer (a transmission of SERVICE REQUESTmessage or a transmission of EXTENDED SERVICE REQUEST message), based onthe category of the application and the ACDC barring informationreceived from the network, the AS layer (i.e., RRC layer) of the UE 100performs the ACDC barring check, and accordingly, determines whether topermit the service request procedure or not.

In the case that the service request procedure is permitted as a resultof the ACDC barring check, the AS layer (i.e., RRC layer) of the UE 100transmits an RRC Connect Request message to an eNodeB 200.

As described above, the service requested by the application which isexecuting in a UE may be differentiated and allowed or barred throughthe ACDC.

<Machine Type Communication (MTC) Communication>

The Machine Type Communication (MTC) means a communication establishedbetween a machine and a machine, in which a person is excluded, and thedevice used in this case is referred to an MTC device. The serviceprovided through an MTC device is discriminated from the communicationservice in which a person intervenes, and may be applied to variousranges of services.

FIG. 10 illustrates an example of the Machine Type communication (MTC)communication.

The Machine Type Communication (MTC) is referred to informationinterchange between MTC devices 100 through an eNodeB 200 in which humaninteraction is not accompanied or information interchange between an MTCdevice and an MTC server 700 through an eNodeB.

The MTC server 700 is an entity that communicates with an MTC device100. The MTC server 700 executes an MTC application and provides aMTC-specific service to the MTC device.

The MTC device 100 is a wireless device that provides an MTCcommunication, and may be fixed or mobile.

However, in coverage of an eNB, a large number of MTC devices may bedisposed. Accordingly, this leads to a result that network congestionbecomes serious more and more.

FIG. 11 illustrates an example to which Extended Access Barring (EAB)for solving a congestion caused by an MTC device.

As shown in FIG. 11, an MTC device is configured as low priority.Further, in order to solve the congestion caused by the MTC device, aneNB broadcasts system information that includes EAB information. Thesystem information including the EAB information may be systeminformation block (SIB) type 14.

TABLE 3 SIB Type14 description eab-BarringBitmap Bitmap of EAB foraccess class (AC) 0 to 9. In the bitmap, the leftmost bit is for AC 0,and the second bit is for AC 1. eab-Category Indicates the category ofUEs for which EAB applies. eab-Common The EAB parameters applied for allPLMN. eab-PerPLMN-List The EAB parameters per PLMN, listed in the orderas the PLMN.

In addition, a network forwards the configuration information on whethera specific MTC device needs to apply EAB, that is, EAB configurationinformation with being included in NAS configuration Management Object(MO) to the specific MTC device. As such, low priority and EAB areconfigured, in the MTC device, except for a case corresponding to anEmergency call, a Mobile Terminated (MT) access or a high priorityaccess class (e.g., AC11-15), for the corresponding NAS signalingrequest procedure (e.g., Attach request procedure, TAU/RAU requestprocedure, Service request procedure, Extended service requestprocedure, Data service request procedure, etc.), the NAS layer informsan indication on whether to apply EAB to an RRC layer, and the RRC layerperforms an access control by applying EAB when performing an RRCconnection establishment procedure with respect to the correspondingrequest with the EAB application indication.

Accordingly, as shown in FIG. 11, when an application (APP) layer of theMTC device 100 notifies that a data transmission is required, the NASlayer determines to apply EAB based on the EAB configuration. Inaddition, the NAS layer forwards a NAS signaling request to the RRClayer. At this time, together with the NAS signaling request, the EABapplication indication is forwarded together.

The RRC layer of the MTC device determines whether the RRC connectionestablishment request corresponds to the EAB application based on theEAB application indication. In the case that the EAB is applied, atransmission of an RRC connection establishment request message by theRRC layer is barred (or prohibited).

<Cellular Internet of Things (CIoT) Communication>

MTC communication is also called IoT (Internet of Things) communicationbecause there is no human intervention. Performing IoT communicationbased on cellular network rather than wireless LAN like Wi-Fi is calledCIoT. Unlike wireless LAN, CIoT supports communication which is notbased on IP as well as IP-based communication.

Meanwhile, in order to support the CIoT service, the 3GPP has improvedthe physical layer, that is, RAT (Radio Access Technology). The improvedRAT is called NB-IoT (Narrowband-IoT).

The improved RAT for the NB-IoT uses a physical layer which is optimizedfor very low power consumption (e.g., carrier bandwidth is 180 kHz andsubcarrier spacing is 3.75 kHz or 15 kHz).

<Next Generation Mobile Communication Network>

Thanks to the success of LTE (Long Term Evolution) and LTE-Advanced(LTE-A) for 4G mobile communication, interest in the next generation,namely 5G mobile communication increases and thus study on the 5G mobilecommunication is progressing.

The 5th generation mobile telecommunications defined by theInternational Telecommunication Union (ITU) refers to communicationproviding a data transmission rate of up to 20 Gbps and an actualminimum transmission rate of at least 100 Mbps anywhere. The officialname of the 5th generation mobile telecommunications is ‘IMT-2020’ andITU's goal is to commercialize the ‘IMT-2020’ worldwide by 2020.

The ITU proposes three usage scenarios, for example, enhanced MobileBroadband (eMBB), massive Machine Type Communication (mMTC) and UltraReliable and Low Latency Communications (URLLC).

First, the URLLC relates to a usage scenario requiring high reliabilityand low latency. For example, services such as automatic driving,factory automation, augmented reality require high reliability and lowlatency (e.g., a delay time of less than 1 ms). The delay time ofcurrent 4G (LTE) is statistically 21 to 43 ms (best 10%) and 33 to 75 ms(median). This is insufficient to support a service requiring a delaytime of 1 ms or less.

Next, the eMBB usage scenario relates to a usage scenario requiringmobile ultra-wideband.

It seems difficult for this ultra-wideband high-speed service to beaccommodated by the core network designed for legacy LTE/LTE-A.

Therefore, in the so-called fifth generation mobile communication, aredesign of the core network is urgently required.

FIG. 12 is an exemplary diagram illustrating a predicted structure of anext generation mobile communication in terms of a node.

Referring to FIG. 12, the UE is connected to a data network (DN) througha next generation RAN (Radio Access Network).

The Control Plane Function (CPF) node as shown may perform all or a partof the MME (Mobility Management Entity) function of the fourthgeneration mobile communication, and all or a part of the control planefunction of the Serving Gateway (S-GW) and the PDN-gateway (P-GW) of thefourth generation mobile communication. The CPF node includes an Accessand Mobility Management Function (AMF) node and a Session ManagementFunction (SMF) node.

The user plane function (UPF) node shown in the figure is a type of agateway over which user data is transmitted and received. The UPF nodemay perform all or part of the user plane functions of the S-GW and theP-GW of the fourth generation mobile communication.

The PCF (Policy Control Function) node as shown is configured to controla policy of the service provider.

The illustrated Application Function (AF) node refers to a server forproviding various services to the UE.

The Unified Data Management (UDM) node as shown refers to a type of aserver that manages subscriber information, like an HSS (Home SubscriberServer) of 4th generation mobile communication. The UDM node stores andmanages the subscriber information in the Unified Data Repository (UDR).

The Authentication Server Function (AUSF) node as shown authenticatesand manages the UE.

The Network Slice Selection Function (NSSF) node as shown refers to anode for performing network slicing as described below.

On the other hand, in a situation where the UE roams on a visitednetwork, for example, a V-PLMN, there are two schemes for processing asignaling request from the UE. In the first scheme, that is, LBO (localbreak out) scheme, the visited network handles the signaling requestfrom the UE. According to the second scheme, that is, Home Routing (HR)scheme, the visited network transmits a signaling request from the UE tothe home network of the UE.

FIG. 13A is an exemplary diagram illustrating an architecture to which alocal breakout (LBO) scheme is applied when the UE is roaming; FIG. 13Bis an exemplary diagram illustrating an architecture to which an HR(home routed) scheme is applied when the UE is roaming.

As shown in FIG. 13A, in the architecture to which the LBO scheme isapplied, a PCF node in the VPLMN performs an interaction with an AF nodeto generate a PCC rule for a service in the VPLMN. The PCF node in theVPLMN creates the PCC rule based on the policy set therein according tothe roaming agreement with the HPLMN provider.

<Network Slice>

The following describes the slicing of the network to be introduced inthe next generation mobile communication.

Next-generation mobile communication introduces the concept of networkslicing in order to provide various services through a single network.In this connection, slicing a network refers to a combination of networknodes with the functions needed to provide a specific service. Thenetwork node that constitutes the slice instance may be a hardwareindependent node, or it may be a logically independent node.

Each slice instance may consist of a combination of all the nodes neededto construct the entire network. In this case, one slice instance alonemay provide service to the UE.

Alternatively, the slice instance may consist of a combination of someof the nodes that make up the network. In this case, the slice instancemay provide service to the UE in association with other existing networknodes without the slice instance alone providing the service to the UE.In addition, a plurality of slice instances may cooperate with eachother to provide the service to the UE.

The slice instance may differ from a dedicated core network in that allnetwork nodes, including the core network (CN) node and the RAN may beseparated from each other. Further, the slice instance differs from thededicated core network in that the network nodes may be logicallyseparated.

FIG. 14A is an exemplary diagram illustrating an example of anarchitecture for implementing the concept of network slicing.

As can be seen from FIG. 14A, the core network (CN) may be divided intoseveral slice instances. Each slice instance may contain one or more ofa CP function node and a UP function node.

Each UE may use a network slice instance corresponding to its servicethrough RAN.

Unlike the case shown in FIG. 14A, each slice instance may share one ormore of a CP function node, and a UP function node with another sliceinstance. This will be described with reference to FIG. 14b below.

FIG. 14B is an exemplary view showing another example of an architecturefor implementing the concept of network slicing.

Referring to FIG. 14B, a plurality of UP function nodes are clustered,and a plurality of CP function nodes are also clustered.

Further, referring to FIG. 14B, slice instance #1 (or instance #1) inthe core network includes a first cluster of an UP function node.Moreover, the slice instance #1 shares the cluster of the CP functionnode with slice instance #2 (or instance #2). The slice instance #2includes a second cluster of an UP function node.

The illustrated NSSF selects a slice (or instance) that can accommodatethe UE's service.

The illustrated UE may use the service #1 via the slice instance #1selected by the NSSF and may use the service #2 via the slice instance#2 selected by the NSSF.

<Interworking with Legacy 4th Generation Mobile Communication System>

Even if the UE leaves the coverage of the next generation RAN (RadioAccess Network), the UE must be able to receive service via a 4G mobilecommunication system. This is called interworking. Hereinafter,interworking will be described in detail.

FIG. 15A shows an architecture for interworking when the UE is notroaming, and FIG. 15B shows an architecture for interworking when the UEis roaming.

Referring to FIG. 15A, when the UE does not roam, E-UTRAN and EPC forlegacy 4th generation LTE, and 5th generation mobile communicationnetwork may be interworked with each other. In FIG. 15A, a packet datanetwork gateway (PGW) for a legacy EPC is divided into a PGW-U, which isresponsible for only the user plane, and a PGW-C, which is responsiblefor the control plane. Moreover, the PGW-U is merged into the UPF nodeof the fifth-generation core network, and the PGW-C is merged into theSMF node of the fifth-generation core network. Moreover, the Policy andCharging Rules Function (PCRF) for the legacy EPC may be merged into thePCF of the 5th generation core network. Moreover, the HSS for the legacyEPC may be merged into the UDM of the 5th generation core network.

The UE may access the core network through the E-UTRAN. Alternatively,the UE may access the core network through the 5G radio access network(RAN) and the AMF.

Referring to FIGS. 15A and 15B while comparing FIGS. 15A and 15B, whenthe UE roams on a Visited Public Land Mobile Network (VPLMN), the dataof the UE is delivered via the Home PLMN (HPLMN).

Meanwhile, the N26 interface shown in FIGS. 15A and 15 refers to aninterface connected between the MME and the AMF node to facilitateinterworking between the EPC and the NG core. This N26 interface may beselectively supported depending on the network operator. That is, forinterworking with the EPC, the network operator may provide the N26interface or may not provide the N26 interface.

<Disclosure of the Present Specification>

In a conventional 4G mobile communication system, i.e., an LTE system,various access control mechanisms (e.g., ACB, EAB, ACDC, SSAC, etc.)have been developed. When the UE is switched from an RRC idle state toan RRC connected mode for transmission of data or signaling, theconventional access control mechanism is performed. However, when aplurality of access control mechanisms operates, there is no effectivemutual processing method. Further, when the UE is in an RRC connectedmode, an existing access control mechanism is not applied and thus thereis a problem that access control cannot be efficiently performed. Inparticular, when the UE is in an RRC connected mode, there is a problemthat access control for signaling for session management cannot beperformed.

As described above, an architecture for a next generation (i.e.,NextGen) (so-called 5G) mobile communication system (also referred to asso-called LTE-A Pro) has recently been discussed. However, existingaccess control mechanisms have an inefficient problem and thus it is notappropriate to apply the existing access control mechanisms to a nextgeneration mobile communication system.

Accordingly, the disclosure of the present specification providesproposals for solving the above-mentioned problems.

I. First Disclosure

In the first disclosure, a next generation (i.e., NextGen) (so-called5G) mobile communication system (also referred to as so-called LTE-APro) provides an efficient access control scheme of a UE. When brieflysummarizing the first disclosure, a NAS layer of the UE may optionallytransfer an access category or a call type and/or an RRC establishmentcause to an AS layer. A detailed description thereof is as follows.

FIG. 16 is a signal flow diagram illustrating an exemplary procedureaccording to a first disclosure of the present specification.

In order to perform access control, the network may transfer accesscategory mapping information in a Management Object (MO) form based onOpen Mobile Alliance (OMA) Device Management (DM) to the UE. The accesscategory mapping information may be set based on a Mobility Management(MM) procedure of the NAS layer, a Session Management (SM) procedure ofthe NAS layer, an RRC procedure, an application, an access class, delaysensitivity (or delay tolerant), a type of the UE, and a service type.

When the AS layer (i.e., RRC layer) of the UE receives access controlrelated information/parameter (e.g., barring ratio, setup information onwhether barring is applied (ON/OFF)) from the base station/network, theAS layer transfers the information to the application layer (or IMSlayer) of the UE. In this case, the AS layer (i.e., RRC layer) maytransfer the access control related information/parameter to theapplication layer (or IMS layer) through the NAS layer.

The NAS layer may determine each access category for performing accesscontrol for each MM procedure thereof, SM procedure thereof, RRCprocedure, application, access class, delay sensitivity, type of the UE,or service type. Here, the MM procedure of the NAS layer may include anAttach procedure (i.e., transmission of a attach request message), aregistration procedure (i.e., transmission of a registration requestmessage), a Tracking Area Update (TAU) procedure (i.e., transmission ofa TAU request message), a registration update procedure (i.e.,transmission of a registration update request message), a servicerequest procedure (i.e., transmission of a service request message ortransmission of a control plane service request message, transmission ofan extended service request message), a connection request procedure(i.e., transmission of a connection request message), and a detachprocedure. The SM procedure of the NAS layer may include a PDU sessionprocedure (i.e., transmission of a PDU session request message), a PDUsession modification procedure (i.e., transmission of a Modify PDUSession Request message), a PDU session deactivation procedure (i.e.,transmission of a Deactivate PDU Session Request message), a PDU sessiondisconnection procedure (i.e., transmission of a PDU session disconnectrequest message), a PDN connection request procedure (i.e., transmissionof a PDN connectivity request message), a PDN disconnection procedure(i.e., transmission of a PDN disconnection request message), a bearerresource allocation request procedure (i.e., transmission of a bearerresource allocation request message), and a bearer resource modificationrequest procedure (i.e., transmission of a bearer resource modificationrequest message). The RRC procedure may include an RRC connectionrequest procedure, an RRC connection resumption procedure, an RRCconnection reestablishment request procedure, an RRC inactive requestprocedure, and an RRC active request procedure.

Table 4 shows an exemplary access category for each procedure.

TABLE 4 Procedure Category Attach/registration request procedureCategory 1 TAU/registration update procedure Category 2 Service requestprocedure Category 3 PDU session request procedure Category 4 PDUsession modification procedure Category 5 PDU session disconnectionprocedure Category 6 PDN connection request procedure Category 7 PDUsession deactivation procedure Category 8 RRC connection requestprocedure Category 9 RRC connection resumption request procedureCategory 10 Response to Mobile Terminated (MT) service Category 11Emergency service Category #99

In Table 4, the higher the number of access category, the higher apriority and the lower a barring rate. That is, a procedure having ahigh number of access category may have a high probability to passthrough a barring check for access control and thus high connectivity isguaranteed. In contrast, the higher the number of access category, thelower a priority and the higher the barring rate. That is, a procedurehaving a high number of access category may have a lower probability topass through a barring check for access control and thus lowconnectivity is guaranteed. Further, for an access category of aparticular number, a barring check may be especially skipped or barredto be differentiated. For example, as the access category #99 is set toan emergency service, a barring check of the emergency service may beskipped to be connected.

Alternatively, the NAS layer may determine each of an MM procedurethereof, an SM procedure thereof, an RRC procedure, and a call typeand/or an RRC establishment cause for performing access control for eachapplication.

Table 5 shows an exemplary call type and/or RRC establishment cause ofeach procedure.

TABLE 5 Procedure Call type and/or RRC establishment causeAttach/registration request procedure Call type = (mobile) originatingattach and/or RRC establishment cause = mo-attach TAU/Registrationupdate procedure Call type = (mobile) originating TAU and/or RRCestablishment cause = mo-TAU Service request procedure Call type =(mobile) originating service and/or RRC establishment cause = mo-servicePDU session request procedure Call type = (mobile) originating PDUsession and/or RRC establishment cause = mo-pdusession PDU sessionmodification procedure Call type = (mobile) originating modify PDUsession and/or RRC establishment cause = mo- modifypdusession PDUsession disconnection procedure Call type = (mobile) originating PDUsession disconnect and/or RRC establishment cause = mo-pdusessiondisconnect PDN connection request procedure Call type =(mobile) originating PDN connectivity and/or RRC establishment cause =mo- PDNconnectivity PDU session deactivation procedure Call type =(mobile) originating deactivate PDU session and/or RRC establishmentCause = mo- deactivatePDUsession RRC connection request procedure Calltype = (mobile) originating RRCconnection and/or RRC establishment cause= mo- RRCconnection RRC connection resumption request Call type =(mobile) originating procedure RRCconnectionresume and/or RRCestablishment cause = mo-RRCconnectionresume, etc.

The AS layer (i.e., RRC layer) of the UE may set a call type and/or anRRC establishment cause of the RRC procedure. Alternatively, after thebase station sets a call type and/or an RRC establishment cause, thebase station may provide the call type and/or the RRC establishmentcause to the AS layer (i.e., RRC layer) of the UE. The NAS layer of theUE may set an MM procedure thereof, an SM procedure thereof, and a calltype and/or an RRC establishment cause for each application.Alternatively, after the base station sets a call type and/or an RRCestablishment cause, when the base station provides the MM procedure ofthe NAS layer, the SM procedure of the NAS layer, and the call typeand/or the RRC establishment cause to the AS layer of the UE, the ASlayer of the UE may transfer the MM procedure of the NAS layer, the SMprocedure of the NAS layer, and the call type and/or the RRCestablishment cause to the NAS layer.

The network node (e.g., base station) may provide barring information(including information indicating skipping of the barring check) foraccess control for the each access category or call type and/or RRCestablishment cause to the AS layer (i.e., RRC layer) of the UE througha Master Information Block (MIB) and a System Information Block (SIB).The SIB information may be defined and included in SIB2 or SIB14 or anew SIB (xx).

Further, when the application layer (or including the IMS layer)requests a call for a Mobile Originating (MO) service to the NAS layeror requests data transmission to the NAS layer, the NAS layer may divideand set call types and RRC establishment causes of Table 6 for the MOservice.

TABLE 6 Division Call type and/or RRC establishment cause (general,normal) call or data Call type: (Mobile) originating calls, “originatingMMTEL voice for MMTEL voice”, “originating MMTEL video for MMTEL video”,“originating SMSoIP for SMS over IP”, “originating SMS for SMSRRCestablishment cause: set to MO data or access category 12 MT serviceCall type: (Mobile) terminating callsRRC establishment cause: set to MTaccess or access category 11 (emergency data, exception data) call Calltype: (Mobile) originating exception (or MO or data or signalingexception calls, etc.) or (Mobile) originating calls or (Mobile)originating signalling RRC establishment cause: set to MO exception (orMO exception data, MO exception signalling, etc.) or access category 13Low delay sensitive (or delay Call type: (Mobile) originating calls,“originating tolerant) UE MMTEL voice for MMTEL voice”, “originatingMMTEL video for MMTEL video”, “originating SMSoIP for SMS over IP”,“originating SMS for SMSRRC establishment cause: set to DelayTolerant oraccess category 14 EAB Call type: (Mobile) originating calls,“originating MMTEL voice for MMTEL voice”, “originating MMTEL video forMMTEL video”, “originating SMSoIP for SMS over IP”, “originating SMS forSMSRRC establishment cause: set to EAB or access category 15 Accessclass 3: Call type: (Mobile) originating calls, “originating MMTEL voicefor MMTEL voice”, “originating MMTEL video for MMTEL video”,“originating SMSoIP for SMS over IP”, “originating SMS for SMSRRCestablishment cause: set to MO data or access category 16 Access class10 Call type: emergency callRRC establishment cause: set to emergency oraccess category 17

In this case, the application layer of the UE may provideinformation/indication that distinguishes delay data and exception datato the NAS layer.

When starting an NAS signaling request (i.e., MM procedure and/or SMprocedure) for data transmission, the NAS layer of the UE may set eachof an access category or a call type and/or an RRC establishment cause,as described above to provide the access category or the call typeand/or the RRC establishment cause to the AS layer (i.e., RRC layer).

When starting an NAS signaling request (MM procedure and/or SMprocedure) for data transmission, a plurality of access categories maybe (simultaneously) determined. In this case, the NAS layer may provideonly a high (e.g., highest) access category or a lower (e.g., lowest)access category of the plurality of access categories to the AS layer(i.e., RRC layer). Alternatively, the NAS layer may provide all of theplurality of access categories to the AS layer (i.e., RRC layer).Alternatively, the NAS layer may select only one access category of theplurality of access categories based on at least one of an NAS setupManagement Object (MO), a new MO, setup of the UE, and an operatorpolicy and provide the one access category to the AS layer.

The AS layer performs a barring check for access control based on thereceived information (i.e., access category mapping information or acall type and/or an RRC establishment cause) and access control relatedinformation/parameter received from the network through a MasterInformation Block (MIB) or a System Information Block (SIB). In thiscase, the barring check may differentiate an NAS signaling connectionrequest based on a probability. Alternatively, the barring check maydifferentiate by determining whether to bar access based on a bitmap. Inthis case, an access category in which the NAS layer provides to the ASlayer may be a high (i.e., highest) access category or a low (i.e.,lowest) access category selected by the NAS layer. When the NAS layerprovides all of a plurality of access categories to the AS layer, the ASlayer may select a high (or highest) access category or a low (i.e.,lowest) access category of the plurality of access categories.Thereafter, the AS layer performs access control based on the selectedaccess category, a call type and/or an RRC establishment cause receivedfrom the NAS layer, and access control information/parameter receivedthrough the MIB or the SIB from the network. Alternatively, the AS layermay select one of a plurality of access categories based on a NAS setupManagement Object (MO), a new MO, setup of the UE, an operator policy,and MIB/SIB information and perform access control based on the selectedaccess category, the call type and/or the RRC establishment causereceived from the NAS layer, and access control information/parameterreceived from the network through the MIB/SIB.

When a plurality of access categories is (simultaneously) determined, aparticular access category (e.g., a common/general access category or aspecific access category) of the plurality of access categories may beselected, and operations of the NAS layer and the AS layer may beperformed based on the particular access category.

Alternatively, when a plurality of access categories is (simultaneously)determined, the NAS layer and the AS layer each may perform an operationfor access control of each access category. In this way, when the ASlayer performs an operation for access control of each access category,the AS layer may provide information (i.e., success or failure) on aresult of a barring check for access control of each access category tothe NAS layer. When success information is received, the NAS layer mayperform an operation for additional access control of each accesscategory. When failure information is received, the NAS layer may stopan entire operation for access control of each access category or stoponly an operation for access control of the corresponding accesscategory and perform an operation for access control of other accesscategories.

In this case, when the NAS layer receives information on success orfailure of access control of each access category from the AS layer, theNAS layer may store the information on success or failure for eachaccess category.

When barring (i.e., failure) is determined as a result of a barringcheck for access control of the particular access category, an NASsignaling request for the same access category may not be started (untilreceiving information representing barring alleviation of thecorresponding access category from the AS layer). When passing (i.e.,success) is determined as a result of a barring check for access controlof the particular access category, an NAS signaling request for the sameaccess category may be started. Further, the AS layer (i.e., RRC layer)may also store information (i.e., information on success and failure)about the result of the barring check for access control of each accesscategory. In a case of barring (i.e., failure), the AS layer may drive abarring timer for each access category. When a barring timer for eachaccess category has expired, the AS layer may provide informationrepresenting that barring of each access category is alleviated to theNAS layer.

Further, when the NAS layer provides all of a plurality of accesscategories or any one of a plurality of access categories to the ASlayer, the NAS layer may additionally provide transaction ID of eachaccess category. The AS layer (i.e., RRC layer) may also storeinformation (i.e., success or failure) on a result of a barring checkfor access control of each access category. In this case, the AS layermay together store the transaction ID. In the case of barring (i.e.,failure), a barring timer for each access category may operate inconjunction with a transaction ID. When the barring timer for eachaccess category has expired, the AS layer may provide informationrepresenting that barring of each access category is alleviated andtransaction ID to the NAS layer.

In a situation in which the plurality of access categories aredetermined, even when a plurality of call types and/or a plurality ofRRC establishment causes are determined, the above-described descriptionon an operation of the NAS layer and the AS layer of the UE may beequally applied.

Further, when transmitting an RRC connection establishment requestmessage for transmitting the NAS signaling request, the AS layer of theUE may provide access category or call type and/or an RRC establishmentcause information to the network node (e.g., base station).

Therefore, according to the access control improved by the firstdisclosure, the UE may perform an access control mechanism regardless ofwhether the UE is in an RRC idle state, an RRC connected mode, or an RRCinactive mode.

In the RRC idle state, an MM procedure of the NAS layer is generallyperformed. Therefore, for a mobile originating (MO) service (e.g., MOdata or MO calls) in the RRC idle state, the access control mechanismimproved according to the first disclosure is performed. However, in theRRC connected mode (or RRC inactive mode), an SM procedure of the NASlayer is generally performed. In this case, the access control mechanismimproved according to the first disclosure is performed.

According to a conventional LTE system, in order for the NAS layer ofthe UE to perform an MM procedure in an RRC idle state, when the NASlayer transfers a call type and/or an RRC establishment cause to the ASlayer while transferring an NAS signaling request message (e.g., attachrequest message, TAU request message, service request message, CPservice request message, extended service request message, or connectionrequest message) to the AS layer, the AS layer performs a barring checkfor access control based on call type and/or RRC establishment causeinformation.

However, according to the first disclosure, in order for the NAS layerof the UE to perform an MM procedure in the RRC idle state, the NASlayer provides access category or call type and/or RRC establishmentcause information together with an NAS signaling request message to theAS layer of the UE. Therefore, the AS layer of the UE performs a barringcheck for access control based on the access category or call typeand/or RRC establishment cause information.

According to the first disclosure, in order for the NAS layer of the UEto perform the SM procedure in an RRC connected mode (or RRC inactivemode), the NAS layer transfers access category or call type and/or RRCestablishment cause information together with an NAS signaling requestmessage (e.g., PDU session request message, PDU session modificationrequest message, PDU session disconnection request message, PDNconnection request message, PDU session inactive request message, andESM NAS layer message) to the AS layer of the UE. Therefore, the ASlayer of the UE performs a barring check for access control based on theaccess category or call type and/or RRC establishment cause information.

Further, according to the first disclosure, when the UE in the RRCinactive state or the RRC active state performs an RRC procedure, the UEmay perform a barring check for access control based on the accesscategory or call type and/or RRC establishment cause information.

According to the first disclosure, when the UE is in an RRC connectedmode (or RRC inactive mode), after the NAS layer of the UE performs thebarring check for access control based on the access category or calltype and/or RRC establishment cause information for an NAS signalingrequest message for performing an SM procedure, if the barring check ispassed, the NAS layer includes the NAS signaling request message in theRRC message and transmits the RRC message to the network. The RRCmessage may be any one of an RRC connection setup complete message, anRRC connection resume complete message, an RRC connectionreestablishment complete message, an RRC connection reconfigurationcomplete message, an RRC active request or complete message, an RRCinactive request or complete message, a UE capability informationmessage, a UL information transfer message, or a new RRC message for anRRC connected mode.

II. Second Disclosure

The second disclosure proposes an efficient access control scheme of aUE in a next generation (i.e., NextGen) (so-called 5G) mobilecommunication system (also referred to as so-called LTE-A Pro). Thedifference of the second disclosure from the first disclosure is asfollows. According to the first disclosure, the NAS layer of the UEselectively transfers an access category or a call type and/or an RRCestablishment cause to the AS layer. According to the second disclosure,the NAS layer of the UE may transfer a call type and/or an RRCestablishment cause together with an access category to the AS layer.

A detailed description thereof is as follows.

FIG. 17 is a signal flow diagram illustrating an exemplary procedureaccording to a second disclosure of the present specification.

In order to perform access control of the UE, the network determines anaccess category based on an MM procedure of the NAS layer, an SMprocedure of the NAS layer, an RRC procedure, an application, an accessclass, delay sensitivity, a type of a UE, and a service type. Thenetwork may provide the access category to the UE through a ManagementObject (MO) based on OMA DM.

Here, the MM procedure and the SM procedure of the NAS layer are thesame as those described in the first disclosure. The RRC procedure isthe same as that described in the first disclosure.

That is, each access category for access control may be set for each MMprocedure of the NAS layer, SM procedure of the NAS layer, RRCprocedure, application, access class, delay sensitivity, type of the UE,or service type.

An illustrative access category for each procedure is shown in Table 4.

Alternatively, each call type and/or RRC establishment cause for accesscontrol may be set for each MM procedure of the NAS layer, SM procedureof the NAS layer, RRC procedure, and application.

An exemplary call type and/or RRC establishment cause of each procedureare(is) shown in Table 5.

Further, when the application layer (or including the IMS layer)requests a call for a Mobile Originating (MO) service to the NAS layeror when the application layer (or including the IMS layer) requests datatransmission to the NAS layer, the NAS layer may classify and set a calltype and an RRC establishment cause of Table 6 for the MO service.

The AS layer performs a barring check for access control based on theinformation (i.e., access category mapping information and a call typeand/or an RRC establishment cause) received from the application layer(or including the IMS layer) or the NAS layer and access controlinformation/parameter received from the network through a MasterInformation Block (MIB) or a System information block (SIB).

In addition, the description of the second disclosure is the same as thedescription of the above-described first disclosure and therefore adetailed description thereof may be omitted and the description of thefirst disclosure will be used.

III. Third Disclosure: Overload Control

In the third disclosure, it is assumed that an NAS layer of the UE mayaccess to both a next generation core network (so-called NG core) and anEvolved Packet Core (EPC) of 4G This may mean that the NAS layer of theUE supports a dual protocol stack. Alternatively, the NAS layer of theUE may use a single integrated protocol stack.

In general, when radio access technology (RAT) of the base stationaccessed to the UE is 5G NR, the UE may be connected to a nextgeneration core network (so-called NG core) through the base station.However, in the third disclosure, even if RAT of the base stationaccessed to the UE is 4G LTE (or referred to as E-UTRA), it isconsidered that the UE may be connected to the next generation corenetwork (so-called NG core) through the base station.

FIG. 18 is a signal flow diagram illustrating an exemplary procedureaccording to the third disclosure of the present specification.

In the above-described situation, according to the third disclosure, theAS layer of the UE provides RAT information of a currentlyaccessed/connected base station to the NAS layer of the UE. The NASlayer of the UE recognizes RAT of the currently accessed/connected basestation by the RAT information received from the AS layer (i.e., RRClayer).

In this case, when the NAS layer of the UE requests NAS signalingconnection, the AS layer (i.e., RRC layer) of the UE performs a barringcheck for access control before establishing RRC connection for the NASsignaling connection request. In this case, the NAS layer of the UEprovides necessary information when the AS layer (i.e., RRC layer)performs a barring check. Specifically, the NAS layer of the UEdetermines necessary information when the AS layer performs a barringcheck based on the currently accessed/connected RAT information receivedfrom the AS layer. For example, when RAT currently accessed to the UE is4G LTE (i.e. E-UTRA), the NAS layer of the UE may provide informationsuch as a call type and/or an RRC establishment cause, EAB indication,overriding EAB indication, and ACDC access category that may be used forthe 4G E-UTRAN to the AS layer (i.e., RRC layer) of the UE.Alternatively, when RAT currently accessed to the UE is 5G NR, the NASlayer of the UE may provide information such as access category for a 5GNG core to the AS layer (i.e., RRC layer) of the UE. Alternatively, whenRAT currently accessed to the UE is 5G NR, the NAS layer of the UE mayprovide call type and/or RRC establishment cause information that may beused for the 4G E-UTRAN together with the access category to the ASlayer (i.e., RRC layer) of the UE. Alternatively, although RAT currentlyaccessed to the UE is 4G LTE (i.e. E-UTRA), when the NAS layer of the UEprovides an access category to the AS layer, the AS layer (i.e., RRClayer) of the UE may set an appropriate RRC establishment cause based onthe access category.

Although the NAS layer of the UE provides call type and/or RRCestablishment cause information to the AS layer (i.e., RRC layer) of theUE together with the access category or although the NAS layer of the UEprovides only an access category, when the AS layer determines call typeand/or RRC establishment cause information based on the access category,the AS layer of the UE performs a barring check for access controlaccording to the first disclosure or the second disclosure.

When passing is determined instead of barring as a result of the barringcheck, the AS layer transmits an RRC procedure message (e.g., RRCconnection request message).

Therefore, the base station transmits an N2 signaling message to the AMFusing an N2 interface of FIG. 12. In this case, for overload control,the base station includes an RRC establishment cause in the N2 signalingmessage and transfers the N2 signaling message to the AMF.

Therefore, when the AMF performs overload control, the AMF refers to theRRC establishment cause value. Here, the overload control means that theAMF sends an overload start command to the base station based on the RRCestablishment cause value in a congestion/overload situation of thenetwork. When the base station receives the overload start command, thebase station may reject or accept an RRC connection request of the UEbased on the RRC establishment cause value. When the RRC connectionrequest is rejected, the base station may include an (extended) waittime value in the rejection message and transmit the rejection messageto the UE.

Therefore, the AS layer (i.e., RRC layer) of the UE transfers the(extended) wait time value to the NAS layer of the UE together with anindication representing rejection of the NAS signaling request.

The NAS layer of the UE drives a timer according to the (extended) waittime value (when the back-off timer previously received from the networkdoes not operate). The NAS layer of the UE does not additionally performan NAS signaling request until the timer has expired. Similarly, the ASlayer (i.e., RRC layer) of the UE does not perform an RRC connectionrequest until the timer according to the (extended) wait time value hasexpired.

When a congestion/overload situation of the core network is solved, theAMF sends an overload stop command to the base station. Therefore, thebase station no longer performs overload control for an RRC connectionrequest of the UE. That is, the base station may accept an RRC requestincluding a specific RRC establishment cause value.

When the NAS layer of the UE provides only an access category to the ASlayer (i.e., RRC layer) of the UE, the AS layer of the UE performs abarring check for access control, as described in the first disclosureor the second disclosure based on the access category provided in theNAS layer. Thereafter, when a barring check for access control ispassed, the AS layer of the UE transmits an RRC message. Therefore, thebase station transmits an N2 signaling message using the N2 interface tothe AMF. In this case, the base station includes the access category inthe N2 signaling message and transfers the N2 signaling message.Therefore, the AMF performs overload control based on the accesscategory. A detailed description about the overload control adapts theforegoing description.

For the above-described overload control, the AMF should recognize/graspinformation on the access category. That is, information on the accesscategory may be preset in advance by an operator policy or the like.Alternatively, information on the access category may be preset througha policy function node (e.g., PCF) or Unified Data Management (UDM).

When the NAS layer of the UE provides only an access category to the ASlayer (i.e., RRC layer) of the UE, the AS layer of the UE performs abarring check for access control based on the category information.Further, the AS layer of the UE may set an RRC establishment cause basedon the access category. In this case, the AS layer of the UE may obtainaccess category related information through an AT-command. When passingis determined instead of barring as a result of a barring check for theaccess control, the RRC connection procedure is performed. Thereafter,the base station transmits an N2 signaling message using an N2 interfaceto the AMF. In this case, the base station includes and transfers an RRCestablishment cause in the N2 signaling message. Therefore, the AMFperforms overload control based on the RRC establishment cause. Adetailed description about the overload control adapts the foregoingdescription.

The description described in the third disclosure may be applied to anRRC connection release procedure as well as an RRC connection requestprocedure.

IV. Fourth Disclosure

The fourth disclosure describes an operation of performing a barringcheck for access control when the UE is in an RRC connected mode (or RRCinactive mode). When the UE is in an MM connected mode, an RRC connectedmode, or an RRC inactive mode, the description described in the firstdisclosure to the third disclosure may be improved as follows.

IV-1. First Scheme

FIG. 19 is a signal flow diagram illustrating an exemplary procedureaccording to a first scheme of a fourth disclosure.

When the AS layer (i.e., RRC layer) of the UE receives access controlrelated information/parameter (e.g., barring ratio, setup information onwhether barring is applied (ON/OFF)) from the base station/network, theAS layer may transfer the information to the application layer (or IMSlayer) of the UE. In this case, the AS layer (i.e., RRC layer) maytransfer access control related information/parameter to the applicationlayer (or IMS layer) through the NAS layer.

When MO data or MO signaling occurs and when the access control relatedinformation/parameter is received from the AS layer (i.e., RRClayer)/NAS layer, the application layer (or IMS layer) checks whether abarring check for access control is applied. When application of thebarring check is required, the application layer (or IMS layer) mayprovide access control start indication/information to the NAS layer.Alternatively, when MO data or MO signaling occurs, the applicationlayer (or IMS layer) may provide access control startindication/information to the NAS layer instead of determining whetherto apply the barring check. In this case, the application layer (or IMSlayer) may not receive access control related information/parameter fromthe AS layer (i.e., RRC layer).

The NAS layer generates an NAS signaling request (e.g., an NAS signalingrequest for the SM procedure) for MO data or MO signaling and transfersthe NAS signaling request to the AS layer (i.e., RRC layer). In thiscase, the NAS layer determines an access category for the NAS signalingrequest (e.g., NAS signaling request for the SM procedure) and transfersthe determined access category to the AS layer (i.e., RRC layer).

The AS layer (i.e., RRC layer) performs a barring check for accesscontrol based on the access category received from the NAS layer and theaccess category related information/parameter received from the networknode (e.g., base stations).

In the foregoing description, a more detailed description ofdetermination of an access category by the NAS layer and a barring checkby the AS layer (i.e., RRC layer) adapts the description of the firstdisclosure to the third disclosure.

When passing is determined instead of barring as a result of the barringcheck, the AS layer (i.e., RRC layer) may transmit an RRC messageincluding the NAS signaling request (e.g., NAS signaling request for theSM procedure) to the base station/network.

In this case, the AS layer (i.e., RRC layer) may include the accesscategory in the RRC message. Alternatively, after determining a calltype and/or an RRC establishment cause based on the access category, theAS layer (i.e., RRC layer) may include the determined call type and/orRRC establishment cause in the RRC message. That is, the RRC message mayinclude the determined call type and/or RRC establishment cause.Alternatively, the RRC message may include the access category, thedetermined call type and/or RRC establishment cause. Because the UE isin an RRC connected mode (or RRC inactive mode), the RRC message may beone of an RRC connection setup complete message, an RRC connectionresume complete message, an RRC connection reestablishment completemessage, an RRC connection reconfiguration complete message, an RRCactive request or complete message, an RRC inactive request or completemessage, a UE capability information message, a UL information transfermessages, or a new RRC message for RRC connected mode.

When barring is determined as a result of the barring check, the ASlayer (i.e., RRC layer) of the UE may provide a failure indication tothe NAS layer and/or the application layer (or IMS layer).Alternatively, the AS layer (i.e., RRC layer) may provide the failureindication to the application layer (or IMS layer) through the NASlayer.

The barring timer is driven. The barring timer may be driven for eachPDU session and/or each NAS signaling request.

Thereafter, when the barring timer has expired, the AS layer (i.e., RRClayer) may provide a barring alleviation indication to the NAS layerand/or the application layer (or IMS layer). Alternatively, the AS layer(i.e., RRC layer) may provide the barring alleviation indication to theapplication layer (or IMS layer) through the NAS layer. Until receivingthe barring alleviation indication, the application layer (or IMS layer)layer cannot transfer MO data or MO signaling to the NAS layer. Further,until receiving the barring alleviation indication, the NAS layer cannottransmit an NAS signaling request to the AS layer (i.e., RRC layer).

When transmission of MO data or MO signaling is complete (when a sessionis terminated), the application layer/IMS layer of the UE transmitsaccess control stop/end indication/information to the NAS layer and/orAS layer (i.e., RRC layer) of the UE. The indication/information meansthat access control of MO data or MO signaling through the correspondingsession has ended. Here, access control start/beginindication/information and the access control stop/endindication/information may be applied for each PDU session and/or eachNAS signaling request. Further, even when the application layer (or IMSlayer) does not receive access control related information/parameterfrom the AS layer (i.e., RRC layer) or the NAS layer, when wanting tostart or end transmission of an MO data or MO signaling request, theapplication layer may provide the access control startindication/information and the access control stop/endindication/information to the NAS layer of the UE.

Here, the barring check for access control may perform MO data or MOsignaling for each session (or for each DNN, for each ID of theapplication, or for each other parameter). Here, each session is mappedto a single access category and thus the access control of the presentinvention may be applied.

The application layer of the UE may perform an operation of general MOdata or MO signaling, and the IMS layer of the UE may perform anoperation of MMTEL voice, MMTEL video, and SMS over IP.

IV-2. Second Scheme

FIG. 20 is a signal flow diagram illustrating an exemplary procedureaccording to a second scheme of a fourth disclosure.

When the AS layer (i.e., RRC layer) of the UE receives access controlrelated information/parameter (e.g., barring ratio, setup information onwhether barring is applied (ON/OFF)) from the base station/network, theAS layer may transfer the information to the application layer (or IMSlayer) of the UE. In this case, the AS layer (i.e., RRC layer) maytransfer the access control related information/parameter to theapplication layer (or IMS layer) through the NAS layer.

When MO data or MO signaling occurs and when the access control relatedinformation/parameter is received from the AS layer (i.e., RRClayer)/NAS layer, the application layer (or IMS layer) may check whetherto apply a barring check for access control. When it is necessary toapply the barring check, the application layer (or IMS layer) mayprovide the access control start indication/information to the NASlayer. Alternatively, when MO data or MO signaling occurs, theapplication layer (or IMS layer) may provide the access control startindication/information to the NAS layer instead of determining whetherto apply the barring check.

The application layer (or IMS layer) may receive an access category fromthe NAS layer. Alternatively, the application layer may receive anaccess control access category from the NAS layer regardless of whetherthe access control is applied.

The application layer (or IMS layer) of the UE may directly perform abarring check for access control based on the received information. Inthe foregoing description, a more detailed description about a barringcheck and determination of an access category by the NAS layer adapt thedescription of the first disclosure to the third disclosure.

When passing is determined instead of barring as a result of the barringcheck, the application layer (or IMS layer) transfers MO data or MOsignaling to the NAS layer. Therefore, the NAS layer generates an NASsignaling request (e.g., 5G SM signaling request) for MO data or MOsignaling and transfers the NAS signaling request to the AS layer (i.e.,RRC layer). Therefore, the AS layer (i.e., RRC layer) may transmit anRRC message including the NAS signaling request to the basestation/network. In this case, the AS layer (i.e., RRC layer) mayinclude the access category in the RRC message. Alternatively, the ASlayer (i.e., RRC layer) may determine a call type and/or an RRCestablishment cause based on the access category and include thedetermined call type and/or RRC establishment cause in the RRC message.That is, the RRC message may include the determined call type and/or RRCestablishment cause. Alternatively, the RRC message may include theaccess category and the determined call type and/or RRC establishmentcause. Because the UE is in an RRC connected mode (or RRC inactivemode), the RRC message may be one of an RRC connection setup completemessage, an RRC connection resume complete message, an RRC connectionreestablishment complete message, an RRC connection reconfigurationcomplete message, an RRC active request or complete message, an RRCinactive request or complete message, an RRC UE capability informationmessage, a UL information transfer messages, or a new RRC message for anRRC connected mode.

When barring is determined as a result of the barring check, a barringtimer is driven. The barring timer may be driven for each PDU sessionand/or each NAS signaling request.

Until the barring timer has expired, the application layer (or IMSlayer) layer cannot transfer MO data or MO signaling to the NAS layer.Further, until the barring timer has expired, the NAS layer cannottransmit an NAS signaling request to the AS layer (i.e., RRC layer).

A barring check for the above-described access control may be performedfor MO data or MO signaling for each session (or for each DNN, each IDof an application, or each other parameter). Here, each session may bemapped to a single access category and thus the access control of thepresent invention may be applied thereto.

The application layer of the UE may perform the operation of general MOdata or MO signaling, and the IMS layer of the UE may perform anoperation of an MMTEL voice, MMTEL video, and SMS over IP.

IV-3. Third Scheme

The NAS signaling request message described in the first scheme and thesecond scheme may be divided into an NAS signaling request message forthe MM procedure and an NAS signaling request message for the SMprocedure. The NAS layer may be divided into an MM entity for the MMprocedure and an SM procedure for the SM procedure. In this case, accesscontrol of the NAS signaling request message for the MM procedure may beperformed by the MM entity of the NAS layer of the UE. The accesscontrol of the signaling request message for the SM procedure may beperformed by the SM entity of the NAS layer of the UE. In this case, theAS layer (i.e., RRC layer) may drive a barring timer for each of the MMprocedure and the SM procedure. The AS layer (i.e., RRC layer) maytransfer failure indication/information and barring alleviationindication/information to the MM entity and the SM entity, respectivelyof the NAS layer.

The description described in the third scheme may be applied to thefirst disclosure to the sixth disclosure of the present specification.

V. Fifth Disclosure

The fifth disclosure provides a scheme of performing an access controloperation for each slice and/or each UE. A scheme according to the fifthdisclosure to be described later may be applied to the first disclosureto the fourth disclosure.

Here, to perform a barring check for access control for each slice (oreach network slice) and for each UE means that the AS layer (i.e., RRClayer) of the UE performs a barring check for access control based onslice (or network slice) related information, i.e., Single Network SliceSelection Assistance information (S-NSSAI) or Slice/Service type (SST)or Slice Differentiator (SD) information.

V-1. First Scheme

A network node (e.g., core network node or base station) provides accesscontrol related parameter information (e.g., barring rate) to the ASlayer (i.e., RRC layer) of the UE through the SIB for each S-NSSAI (andfor each PLMN).

When the NAS layer of the UE sends an NAS signaling request message forMO data or MO signaling to the AS layer (i.e., RRC layer), the NAS layertogether provides S-NSSAI information (e.g., S-NSSAI #1) of thecorresponding NAS signaling request message (or the corresponding PDUsession). Therefore, when the AS layer (i.e., RRC layer) of the UEperforms a barring check of the NAS signaling request message (NASsignaling request for the MM procedure or the SM procedure), the ASlayer performs a barring check based on access control related parameterinformation of S-NSSAI (e.g., S-NSSAI #1) provided from the NAS layerand the corresponding S-NSSAI (e.g., S-NSSAI #1) received from the basestation.

When barring is determined as a result of the barring check, the ASlayer (i.e., RRC layer) of the UE drives a barring timer of thecorresponding S-NSSAI (e.g., S-NSSAI #1) and transfers a failureindication of the corresponding S-NSSAI (e.g., S-NSSAI #1) to the NASlayer.

Until receiving barring alleviation indication/information of thecorresponding S-NSSAI (e.g., S-NSSAI #1) from the AS layer (i.e., RRClayer), the NAS layer does not transmit an NAS signaling request messageof the same S-NSSAI (e.g., S-NSSAI #1) to the AS layer (i.e., RRClayer). However, the NAS layer may transmit an NAS signaling requestmessage of another S-NSSI (e.g., S-NSSAI #2) to the AS layer (i.e., RRClayer).

When the barring timer of the corresponding S-NSSAI (e.g., S-NSSAI #1)has expired, the AS layer (i.e., RRC layer) provides barring alleviationindication/information of the corresponding S-NSSAI (e.g., S-NSSAI #1)to the NAS layer.

In this way, according to the first scheme, a process of a barringcheck, a barring timer, a barring ratio, a barring alleviationindication/information, and a NAS signaling request message for accesscontrol is operated for each S-NSSAI (and PLMN).

V-2. Second Scheme

The network node (e.g., core network node or base station) providesaccess control related parameter information (e.g., barring rate) foreach SST (for each PLMN) to the AS layer (i.e., RRC layer) of the UEthrough the SIB.

When the NAS layer of the UE sends a NAS signaling request message forMO data or MO signaling to the AS layer (i.e., RRC layer), the NAS layertogether provides SST information (e.g., SST #1) of the correspondingNAS signaling request message (or the corresponding PDU session).Therefore, when the AS layer (i.e., RRC layer) of the UE performs abarring check of the NAS signaling request message (NAS signalingrequest for the MM procedure or the SM procedure), the AS layer performsa barring check based on SST information (e.g., SST #1) provided in theNAS layer and access control related parameter information of thecorresponding SST information (e.g., SST #1) received from the basestation.

When barring is determined as a result of the barring check, the ASlayer (i.e., RRC layer) of the UE drives the barring timer of thecorresponding SST (e.g., SST #1) and transfers a failure indication ofthe corresponding SST (e.g., the SST #1) to the NAS layer.

Until receiving barring alleviation indication/information of thecorresponding SST (e.g., SST #1) from the AS layer (i.e., RRC layer),the NAS layer does not send an NAS signaling request message of the sameSST (e.g., SST #1) to the AS layer (i.e., RRC layer). However, the NASlayer may transmit an NAS signaling request message of another SST(e.g., SST #2) to the AS layer (i.e., RRC layer).

When the barring timer of the corresponding SST (e.g., SST #1) hasexpired, the AS layer (i.e., RRC layer) provides a barring alleviationindication/information of the corresponding SST (e.g., SST #1) to theNAS layer.

In this way, according to the second scheme, a process of a barringcheck, a barring timer, a barring ratio, barring alleviationindication/information, and an NAS signaling request message for accesscontrol is performed for each SST (and PLMN).

V-3. Third Scheme

The access control operation described in the first disclosure to thefourth disclosure may be performed for each slice (or for each networkslice) and/or for each DDN and/or for each UE.

Here, a barring check of access control for each slice (or networkslice) and for each DNN (and each UE) is performed as follows. First, ina first process, the AS layer (i.e., RRC layer) of the UE performs abarring check for access control based on slice (or network slice)related information, i.e., S-NSSAI, Slice/Service type (SST), or SliceDifferentiator (SD) information. When passing is determined instead ofbarring as a result of the barring check, in a second process, the ASlayer (i.e., RRC layer) performs a barring check for access controlbased on DNN information. However, when barring is determined as aresult of the barring check, the AS layer (i.e., RRC layer) may providefailure indication (including failure cause value/information) (e.g., acell is barred due to a slice failure) to a superordinate layer (e.g.,NAS layer or IMS layer). Further, a first barring check issuccessful/passed by passing instead of barring as a result of the firstbarring check, but when a second barring check is failed by barring as aresult of the second barring check, the AS layer (i.e., RRC layer) mayprovide a fail indication (including a failure cause value/information)(e.g., a cell is barred due to a DNN failure) to a superordinate layer(e.g. NAS layer or IMS layer).

Therefore, only when all results of the barring check based on slice andDNN information are successful/passed, an NAS signaling request may betransferred to the network.

An access control operation described in the above-described first tofourth disclosures may be performed for each specific criterion (e.g.,for each parameter/information/UE).

For example, the criterion may be a slice (network slice), DNN, QCI,QFI, application ID (App-ID with OS-ID) or the like. Here, it may bedetermined according to the network/operator policy whether to performan access control operation based on which one. When an access controloperation is performed based on a plurality of criteria, if passing isdetermined as a result of the barring check based on a first criterion,the barring check may be performed based on a second criterion. When abarring check according to any criterion is failed, failindication/information (including failure cause information/value) maybe provided to a superordinate layer (NAS layer or IMS layer) instead ofperforming a subsequent barring check based on the criterion.

Accordingly, when a barring check by all criteria is successfullypassed, an NAS signaling request may be sent to the network.

VI. Sixth Disclosure

The access control operations described in the first disclosure to thefifth disclosure is combined with a description according to the sixthdisclosure to be improved as follows.

VI-1. First scheme

When the AS layer (i.e., RRC layer) of the UE receives access controlrelated information/parameter from a network node, the AS layer (i.e.,RRC layer) provides the access control related information/parameter tothe NAS layer or the application layer (e.g., IMS layer or MMTEL layer).Thereafter, when a request for data/signaling, MMTEL signaling (MMTELvoice, MMTEL video, and MMTEL signaling for SMS over IP) to transmitoccurs, the application layer (e.g., IMS layer or MMTEL layer) transfersthe request to the NAS layer of the UE. In this case, a start/stopindication of the session may be together transferred. Thereafter, theNAS layer of the UE determines an access category according to thedescription of the first disclosure to the fifth disclosure. An accessbarring check is performed. Specifically, the barring check may beperformed based on access control related information/parameter from anode provided from the AS layer (i.e., RRC layer) and the accesscategory. When the connection request is passed instead of barring as aresult of the barring check, the NAS layer transfers the connectionrequest to the AS layer (i.e., RRC layer). However, when it isdetermined that the connection request is barred as a result of thebarring check, a barring timer of the corresponding access category isdriven. While the barring timer is driven, the NAS layer does nottransfer the corresponding request to the AS layer (i.e., RRC layer). Afailure indication may be provided to the application layer (e.g., IMSlayer or MMTEL layer). Therefore, until the barring timer of thecorresponding access category has expired, the NAS layer of the UE doesnot perform a corresponding connection request for the correspondingaccess category.

In the case of an SMS over NAS layer, because the NAS layer recognizesthe corresponding connection request, the NAS layer performs a barringcheck for access control based on access control relatedinformation/parameter provided from the AS layer (i.e., RRC layer) andthe determined access category.

When the connection request is passed instead of barring as a result ofthe barring check, the NAS layer transfers the connection request to theAS layer (i.e., RRC layer). However, when it is determined that theconnection request is barred as a result of the barring check, a barringtimer of the corresponding access category is driven. While the barringtimer is driven, the NAS layer does not transfer the correspondingrequest to the AS layer (i.e., RRC layer).

The access category determination operation of the NAS layer follows theabove-described proposals #1 to #5 of the present invention. A detaileddescription of the access category determination operation of the NASlayer follows the description of the first disclosure to the fifthdisclosure.

VI-2. Second Scheme

In the MMTEL layer (or IMS layer), when MMTEL signaling (MMTEL voice,MMTEL video, and MMTEL signaling for SMS over IP) to transmit occurs,the MMTEL layer (or IMS layer) determines an access category accordingto the description of the above-described first disclosure to fifthdisclosure. The MMTEL layer (or IMS layer) performs a barring checkaccording to the description of the first disclosure to the fifthdisclosure. Specifically, a barring check may be performed based onaccess control related information/parameter from a node provided fromthe AS layer (i.e., RRC layer) and an access category transferred fromthe NAS layer.

When the connection request is passed instead of barring as a result ofthe barring check, the request may be transferred to the AS layer (i.e.,RRC layer) through the NAS layer, and the AS layer may transmit therequest to the network. However, when it is determined that theconnection request is barred as a result of the barring check, a barringtimer of the corresponding access category is driven. While the barringtimer is driven, the NAS layer does not transfer the correspondingrequest to the AS layer (i.e., RRC layer). Until the barring timer ofthe corresponding access category has expired, the MMTEL layer (or IMSlayer) does not transfer any request for the same access category to theNAS layer.

The access category determination operation of the MMTEL layer (or IMSlayer) follows the above-described proposals #1 to #5 of the presentinvention. Alternatively, the NAS layer may determine the accesscategory and transfer the access category to the MMTEL layer (or IMSlayer).

VI-3. Third Scheme

Table 7 shows an access category.

TABLE 7 Access category number Conditions of UE Type of access attempt 0All MO signaling for responding to paging 1 When one or more of accessclasses 11 All to 15 are set 2 When the UE performs a service having Allhigh delay allowance and when the UE is a subject of access control foran access category 2 3 All cases except for class of access Emergencycategories 1-2 4 All cases except for class of access MO signalingcategories 1-2 5 All cases except for class of access MMTEL voicecategories 1-2 6 All cases except for class of access MMTEL videocategories 1-2 7 All cases except for class of access SMS categories 1-28 All cases except for class of access MO data that do not belong tocategories 1-2 other access category  9-31 Reserved access category32-63 All cases except for class of access Operator's access classcategories 1-2 and all cases except for a roaming UE

FIGS. 21a to 21d are diagrams illustrating operations of each layer.

Referring to FIG. 21a , the NAS layer may determine an access category,and the AS layer may perform a barring check.

Referring to FIG. 21b , the NAS layer may determine an access category,and the AS layer may perform a barring check. However, for the MMTELrequest, the MMTEL layer may determine an access category, and the ASlayer may perform a barring check.

Referring to FIG. 21c , the AS layer provides access control relatedinformation/parameter to the NAS layer. The NAS layer may determine anaccess category and perform a barring check.

Referring to FIG. 21d , the AS layer provides access control relatedinformation/parameter to the NAS layer and the MMTEL layer. The NASlayer may determine an access category and perform a barring check.However, for the MMTEL request, the MMTEL layer may determine an accesscategory, and the AS layer may perform a barring check.

VI-4. Fourth Scheme

The UE described in the first disclosure to the sixth disclosure mayreceive access control related information such as access categorymapping information, barring information, and UE setup informationthrough OMA DM based MO and/or SIB and/or NAS signaling procedure (e.g.(initial) registration procedure, moving and periodic registrationupdate procedure, UE setup update procedure) and/or (pre-configured)USIM/SIM from the network. In this case, the IMS layer, the NAS layer,and the AS layer (i.e., RRC layer) of the UE may transfer/provideinformation received from the network to other layers (e.g., IMS layer,NAS layer, RRC layer). The UE may obtain information provided from thenetwork node through the AT-command.

Further, the network node may be any one entity or several entities ofan AMF, SMF, (R)AN, a base station (e.g., gNodeB), UPF, UDM, NSSF, AUSF,and PCF.

VI-5. Fifth Scheme

In the description described in the first to sixth disclosures, the IMSrequest message and/or the NAS signaling request message and the RRCsignaling request message are distinguished to perform a barring check.Access category determination for the IMS request message and/or the NASsignaling request message and execution of the barring check for accesscontrol follow the description described in the first to sixthdisclosures.

A barring check to be performed by the AS layer (e.g., RRC layer) may bechanged as follows.

First, the UE may obtain access control related information/parameterssuch as access category and access category mapping information, barringinformation, and UE setup information from a network node through OMA DMbased MO and/or SIB and/or NAS signaling procedure and/or a USIM/SIM.Further, the IMS layer and/or the NAS layer of the UE may obtain accesscontrol related information/parameter through the OMA DM based MO and/orSIB and/or NAS signaling procedure.

Thereafter, when an RRC signaling request is required, in order toobtain access category mapping information on the corresponding RRCsignaling request, the AS layer (i.e., RRC layer) may request the RRCsignaling request to the NAS layer and/or the IMS layer. Thereafter, theNAS layer and/or the IMS layer may provide the access control relatedinformation (including access category mapping information) to the ASlayer (i.e., RRC layer). Alternatively, the NAS layer and/or the IMSlayer may in advance provide the access control related information(including access category mapping information) to the AS layer (i.e.,RRC layer). Alternatively, the AS layer (i.e., RRC layer) may obtain theaccess control related information (including the access categorymapping information) received from the NAS layer and/or the IMS layer orthe network using an AT-command Thereafter, the AS layer (i.e., RRClayer) determines an access category for the corresponding RRC signalingrequest based on the received access control related information(including access category mapping information) and performs a barringcheck. A detailed description about the barring check applies thedescription of the above-described first to sixth disclosures.

In order to obtain access category mapping information, when the ASlayer (i.e., RRC layer) requests the access category mapping informationto the NAS layer and/or the IMS layer, the AS layer (i.e., RRC layer)may include and request information about an RRC signaling request.

When a plurality of access categories are determined by the RRCsignaling request, a highest access category or a lowest access categorymay be selected. Therefore, a barring check may be performed based onthe highest access category or the lowest access category.

Here, the RRC signaling request message means an RRC signaling requestmessage, for example, an RRC connection resume request message, an RRCconnection setup complete message, an RRC connection reconfigurationmessage, an RRC connection request message, a UL information transfermessage, and a UE capability information message requested by anindependent operation of an RRC layer instead of an RRC signalingrequest initiated by an IMS/NAS signaling request.

The description of the above-described first disclosure to the sixthdisclosure may be used in combination.

The foregoing descriptions may be implemented in hardware. This will bedescribed with reference to the drawings.

FIG. 22 is a block diagram illustrating a configuration of a UE and anetwork device according to an embodiment of the present invention.

As shown in FIG. 22, the UE includes a processor 101, a memory 102, anda transceiver 103. The network device 200 or 510 includes a processor201 or 511 and a memory 202 or 512, and a transceiver 203 or 513.

The memories 102 and 202 or 512 store the above-described method.

The processors 101 and 201 or 511 control the memories 102 and 202 or512 and the transceivers 103 and 203 or 513, respectively. Specifically,the processors 101 and 201 or 511 execute each of the above methodsstored in the memories 102 and 202 or 512. The processors 101 and 201 or511 transmit the above-mentioned signals through the transceivers 103and 203 or 513.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the present inventionis not limited to the disclosed exemplary embodiments, but may bemodified, changed, or improved in various forms within the spirit of thepresent invention and the scope described in claims.

What is claimed is:
 1. A method of performing access control in a RadioResource Control (RRC) connected mode, the method comprising:determining, by a Non-Access Stratum (NAS) layer of a terminal, anaccess category when mobile originating (MO) data or mobile originating(MO) signaling to transmit occurs; transferring, by the NAS layer, a NASsignaling message and the access category to an AS layer, when it isdetermined not to bar as a result of a barring check for access controlbased on the access category; and transmitting, by the Access Stratum(AS) layer of the terminal, an RRC message comprising at least one ofthe access category, a call type, and an establishment cause to a basestation.
 2. The method of claim 1, further comprising: receiving, by theAS layer, access control related information from a network;transferring, by the application layer or an IMS layer, an accesscontrol start indication to the NAS layer when the MO data or MOsignaling has occurred; transferring, by the NAS layer, the accesscategory to the AS layer; and performing, by the AS layer, a barringcheck for the access control based on the access category.
 3. The methodof claim 2, further comprising: transferring the received access controlrelated information to the application layer or the IMS layer; anddetermining whether the application layer or the IMS layer shouldperform a barring check for the access control, when MO data or MOsignaling to transmit has occurred in the application layer or the IMSlayer, wherein the application layer or the IMS layer transfers theaccess control start indication to the NAS layer, when it is determinedthat the barring check should be performed.
 4. The method of claim 1,further comprising: transferring, by the application layer or an IMSlayer, an access control start indication to the NAS layer, when the MOdata or MO signaling has occurred in the application layer or the IMSlayer; transferring, by the NAS layer, the access category to the ASlayer; and performing, by the AS layer, a barring check for the accesscontrol based on the access category.
 5. The method of claim 1, furthercomprising: obtaining, by the application layer or an IMS layer, theaccess category from the NAS layer, when MO data or MO signaling hasoccurred in the application layer or the IMS layer; and performing, bythe application layer or the IMS layer, a barring check for the accesscontrol based on the access category.
 6. The method of claim 1, whereinthe NAS signaling message comprises a NAS signaling message for SessionManagement (SM).
 7. The method of claim 6, wherein the NAS signalingmessages for SM comprises at least one of a Packet Data Unit (PDU)session request message, a PDU session modification request message, aPDU session inactive request message, a PDU session disconnectionrequest message, a PDN connection request message, a PDN disconnectionrequest message, a bearer resource allocation request message, and abearer resource modification request message.
 8. The method of claim 1,wherein the RRC message comprises at least one of an RRC connectionsetup complete message, an RRC connection resume complete message, anRRC connection reestablishment complete message, an RRC connectionreconfiguration complete message, an RRC active request or completemessage, an RRC inactive request or complete message, a UE capabilityinformation message, a UL information transfer message, or a new RRCmessage for an RRC connected mode.
 9. The method of claim 1, wherein thebarring check is performed for each of all of the plurality of accesscategories when the determined access category is the multiple number.10. The method of claim 9, further comprising: performing a firstbarring check based on a first category when the determined accesscategory is the multiple number; and performing a second barring checkbased on a second category when it is determined not to bar as a resultof the first barring check.
 11. The method of claim 10, wherein a thirdbarring check is not performed based on a third access category when itis determined to bar as a result of the second barring check.
 12. Aterminal for performing access control in a Radio Resource Control (RRC)connected mode, the terminal comprising: a transceiver; and a processorconfigured to control the transceiver, wherein the processor isconfigured to: determine, by a Non-Access Stratum (NAS) layer of theterminal, an access category, when data or signaling to transmit hasoccurred; transfer, by the NAS layer, a NAS signaling message and theaccess category to the AS layer, when it is determined not to bar as aresult of a barring check for access control based on the accesscategory; and transmit, by the Access Stratum (AS) layer of theterminal, an RRC message comprising at least one of the access category,a call type, and an establishment cause to a base station.